PUBLIC SERVICE CO OF OKLAHOMA (Form: S-3, Received: 04/26/2006 14:04:20)

Registration No. 333-______

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-3

REGISTRATION STATEMENT

Under

THE SECURITIES ACT OF 1933

Public Service Company of Oklahoma

(Exact name of registrant as specified in charter)

Oklahoma	73-0410895
(State or other jurisdiction	(I.R.S. Employer
of incorporation or organization)	Identification No.)

1 Riverside Plaza

Columbus, Ohio 43215

(614) 716-1000

(Address, including zip code, and telephone number,

including area code, of registrant’s principal executive offices)

THOMAS G. BERKEMEYER, Associate General Counsel

AMERICAN ELECTRIC POWER SERVICE CORPORATION

1 Riverside Plaza

Columbus, Ohio 43215

(614) 716-1648

(Name, address, including zip code, and telephone number,

including area code, of agent for service)

It is respectfully requested that the Commission send copies

of all notices, orders and communications to:

Dewey Ballantine LLP

1301 Avenue of the Americas

New York, NY 10019-6092

Attention: E. N. Ellis, IV

___________________

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of the Registration Statement.

___________________

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. [ ]

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, please check the following box. [x]

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ]

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ]

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. [ ]

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. [ ]

CALCULATION OF REGISTRATION FEE

Title of Each Class Of Securities to be Registered	Amount to be Registered	Proposed Maximum Offering Price Per Unit*	Proposed Maximum Aggregate Offering Price*	Amount of Registration Fee
Unsecured Notes	$375,000,000	100%	$375,000,000	$40,125

*Estimated solely for purpose of calculating the registration fee.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The within Prospectus contains the information required by Rule 429 of the Commission under the Securities Act of 1933 with respect to $75,000,000 of Unsecured Notes of the registrant remaining unsold under Registration Statement No. 333-114665 , declared effective April 28, 2004.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED APRIL 26, 2006

PROSPECTUS

PUBLIC SERVICE COMPANY OF OKLAHOMA

1 Riverside Plaza

Columbus, Ohio 43215

614-716-1000

$450,000,000

UNSECURED NOTES

TERMS OF SALE

The following terms may apply to the notes that we may sell at one or more times. A prospectus supplement or pricing supplement will include the final terms for each note. If we decide to list upon issuance any note or notes on a securities exchange, a prospectus supplement or pricing supplement will identify the exchange and state when we expect trading could begin.

-	Mature 9 months to 60 years
-	Fixed or floating interest rate
-	Remarketing features
-	Certificate or book-entry form
-	Subject to redemption
-	Not convertible, amortized or subject to a sinking fund
-	Interest paid on fixed rate notes quarterly or semi-annually
-	Interest paid on floating rate notes monthly, quarterly, semi-annually, or annually
-	Issued in multiples of a minimum denomination

INVESTING IN THESE NOTES INVOLVES RISKS. SEE THE SECTION ENTITLED “RISK FACTORS” BEGINNING ON PAGE 2 FOR MORE INFORMATION.

The notes have not been approved or disapproved by the Securities and Exchange Commission (“SEC”) or any state securities commission, nor have these organizations determined that this prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is ____________, 2006.

THE COMPANY

We generate, sell, purchase, transmit and distribute electric power. We serve approximately 514,000 retail customers in eastern and southwestern Oklahoma. We also sell and transmit power at wholesale to other electric utilities, municipalities, electric cooperatives and non-utility entities engaged in the wholesale power market. Our principal executive offices are located at 1 Riverside Plaza, Columbus, Ohio 43215 (telephone number 614-716-1000). We are a subsidiary of American Electric Power Company, Inc., a public utility holding company, and we are a part of the American Electric Power integrated utility system. The executive offices of American Electric Power Company, Inc. are located at 1 Riverside Plaza, Columbus, Ohio 43215 (telephone number 614-716-1000).

PROSPECTUS SUPPLEMENTS

We may provide information to you about the notes in up to three separate documents that progressively provide more detail: (a) this prospectus provides general information some of which may not apply to your notes, (b) the accompanying prospectus supplement provides more specific terms of your notes, and (c) if not in the accompanying prospectus supplement, the pricing supplement will provide the final terms of your notes. It is important for you to consider the information contained in this prospectus, the prospectus supplement and any pricing supplement in making your investment decision.

RISK FACTORS

Investing in our securities involves risk. Please see the risk factors described in our most recent Annual Report on Form 10-K and all subsequent Quarterly Reports on Form 10-Q , which are incorporated by reference in this prospectus. Before making an investment decision, you should carefully consider these risks as well as other information contained or incorporated by reference in this prospectus. The risks and uncertainties described are those presently known to us. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations, our financial results and the value of our securities.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC. We also file annual, quarterly and special reports and other information with the SEC. You may read and copy any document we file at the SEC’s Public Reference Room at 100 F Street N.E., Room 1580, Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference rooms. You may also examine our SEC filings through the SEC’s web site at http://www.sec.gov .

The SEC allows us to “incorporate by reference” the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information.

We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 (including any documents filed after the date of the initial registration statement and prior to its effectiveness) until we sell all the notes.

·	Annual Report on Form 10-K for the year ended December 31, 2005.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address:

Ms. R. Buonavolonte

American Electric Power Service Corporation

1 Riverside Plaza

Columbus, Ohio 43215

614-716-1000

You should rely only on the information incorporated by reference or provided in this prospectus or any supplement. We have not authorized anyone else to provide you with different information. We are not making an offer of these notes in any state where the offer is not permitted. You should not assume that the information in this prospectus or any supplement is accurate as of any date other than the date on the front of those documents.

RATIO OF EARNINGS TO FIXED CHARGES

The Ratio of Earnings to Fixed Charges for each of the periods indicated is as follows:

Twelve Months Period Ended	Ratio

December 31, 2001	3.00
December 31, 2002	2.49
December 31, 2003	2.96
December 31, 2004	2.14
December 31, 2005	3.40

For current information on the Ratio of Earnings to Fixed Charges, please see our most recent Form 10-K and Form 10-Q. See Where You Can Find More Information .

USE OF PROCEEDS

Unless otherwise stated in a prospectus supplement, the net proceeds from the sale of the notes will be used for funding our construction program and for other general corporate purposes relating to our utility business. These other purposes may include replenishing working capital and redeeming or repurchasing outstanding debt (including the repayment of advances from affiliates) or preferred stock. If we do not use the net proceeds immediately, we temporarily invest them in short-term, interest-bearing obligations. We estimate that our construction costs in 2006 will approximate $278.7 million.

DESCRIPTION OF THE NOTES

General

We will issue the notes under the Indenture dated November 1, 2000 (as previously supplemented and amended) between us and the Trustee, The Bank of New York. This prospectus briefly outlines some provisions of the Indenture. If you would like more information on these provisions, you should review the Indenture and any supplemental indentures that we have filed or will file with the SEC. See Where You Can Find More Information on how to locate these documents. You may also review these documents at the Trustee’s offices at 101 Barclay Street-8W, New York, New York 10286.

The Indenture does not limit the amount of notes that may be issued. The Indenture permits us to issue notes in one or more series or tranches upon the approval of our board of directors pursuant to any supplemental indentures. Each series of notes may differ as to their terms.

The notes are unsecured and will rank equally with all our unsecured unsubordinated debt. For current information on our debt outstanding see our most recent Form 10-K and Form 10-Q . See Where You Can Find More Information .

The notes will be denominated in U.S. dollars and we will pay principal and interest in U.S. dollars. Unless an applicable pricing or prospectus supplement states otherwise, the notes will not be subject to any conversion, amortization, or sinking fund. We expect that the notes will be “book-entry,” represented by a permanent global note registered in the name of The Depository Trust Company, or its nominee. We reserve the right, however, to issue note certificates registered in the name of the noteholders.

In the discussion that follows, whenever we talk about paying principal on the notes, we mean at maturity or redemption. Also, in discussing the time for notices and how the different interest rates are calculated, all times are New York City time and all references to New York mean the City of New York, unless otherwise noted.

The following terms may apply to each note as specified in the applicable pricing or prospectus supplement and the note.

Redemptions

If we issue redeemable notes, we may redeem such notes at our option unless an applicable pricing or prospectus supplement states otherwise. The pricing or prospectus supplement will state the terms of redemption. We may redeem notes in whole or in part by delivering written notice to the noteholders no more than 60, and not less than 30, days prior to redemption. If we do not redeem all the notes of a series at one time, the Trustee selects the notes to be redeemed in a manner it determines to be fair.

Remarketed Notes

If we issue notes with remarketing features, an applicable pricing or prospectus supplement will describe the terms for the notes including: interest rate, remarketing provisions, our right to redeem notes, the holders’ right to tender notes, and any other provisions.

Book-Entry Notes - Registration, Transfer, and Payment of Interest and Principal

Unless otherwise stated in a prospectus supplement, the Depository Trust Company (“DTC”), New York, New York, will act as securities depository for the notes. The notes will be issued as fully-registered notes registered in the name of Cede & Co. (DTC’s partnership nominee) or such other name as may be requested by an authorized representative of DTC. One fully-registered note certificate will be issued for each issue of the notes, each in the aggregate principal amount of such issue, and will be deposited with DTC.

DTC, the world’s largest depository, is a limited-purpose trust company organized under the New York Banking Law, a “banking organization” within the meaning of the New York Banking Law, a member of the Federal Reserve System, a “clearing corporation” within the meaning of the New York Uniform Commercial Code, and a “clearing agency” registered pursuant to the provisions of Section 17A of the Securities Exchange Act of 1934. DTC holds and provides asset servicing for over 2.2 million issues of U.S. and non-U.S. equity issues, corporate and municipal debt issues, and money market instruments from over 100 countries that DTC’s participants (“Direct Participants”) deposit with DTC. DTC also facilitates the post-trade settlement among Direct Participants of sales and other securities transactions in deposited securities, through electronic computerized book-entry transfers and pledges between Direct Participants’ accounts. This eliminates the need for physical movement of securities certificates. Direct Participants include both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, clearing corporations, and certain other organizations. DTC is a wholly-owned subsidiary of The Depository Trust & Clearing Corporation (“DTCC”). DTCC , in turn, is owned by a number of Direct Participants of DTC and Members of the National Securities Clearing Corporation, Fixed Income Clearing Corporation, and Emerging Markets Clearing Corporation, (NSCC, FICC and EMCC, also subsidiaries of DTCC), as well as by the New York Stock Exchange, Inc., the American Stock Exchange LLC and the National Association of Securities Dealers, Inc. Access to the DTC system is also available to others such as both U.S. and non-U.S. securities brokers and dealers, banks, trust companies and clearing corporations that clear through or maintain a custodial relationship with a Direct Participant, either directly or indirectly (“Indirect Participants”). DTC has Standard & Poor’s highest rating: AAA. The DTC Rules applicable to its Participants are on file with the Securities and Exchange Commission. More information about DTC can be found at www.dtcc.com and www.dtc.org .

Purchases of notes under the DTC system must be made by or through Direct Participants, which will receive a credit for the notes on DTC’s records. The ownership interest of each actual purchaser of each note (“Beneficial Owner”) is in turn to be recorded on the Direct and Indirect Participants’ records. Beneficial Owners will not receive written confirmation from DTC of their purchase. Beneficial Owners are, however, expected to receive written confirmations providing details of the transaction, as well as periodic statements of their holdings, from the Direct or Indirect Participant through which the Beneficial Owner entered into the transaction. Transfers of ownership interests in the notes are to be accomplished by entries made on the books of Direct and Indirect Participants acting on behalf of Beneficial Owners. Beneficial Owners will not receive certificates representing their ownership interests in notes, except in the event that use of the book-entry system for the notes is discontinued.

To facilitate subsequent transfers, all notes deposited by Direct Participants with DTC are registered in the name of DTC’s partnership nominee, Cede & Co., or such other name as may be requested by an authorized representative of DTC. The deposit of notes with DTC and their registration in the name of Cede & Co. or such other DTC nominee do not effect any change in beneficial ownership. DTC has no knowledge of the actual Beneficial Owners of the notes; DTC’s records reflect only the identity of the Direct Participants to whose accounts such notes are credited, which may or may not be the Beneficial Owners. The Direct and Indirect Participants will remain responsible for keeping account of their holdings on behalf of their customers.

Conveyance of notices and other communications by DTC to Direct Participants, by Direct Participants to Indirect Participants, and by Direct Participants and Indirect Participants to Beneficial Owners will be governed by arrangements among them, subject to any statutory or regulatory requirements as may be in effect from time to time. Beneficial Owners of notes may wish to take certain steps to augment the transmission to them of notices of significant events with respect to the notes, such as redemptions, tenders, defaults and proposed amendments to the notes documents. For example, Beneficial Owners of notes may wish to ascertain that the nominee holding the notes for their benefit has agreed to obtain and transmit notices to Beneficial Owners. In the alternative, Beneficial Owners may wish to provide their names and addresses to the registrar and request that copies of notices by provided directly to them.

Redemption notices shall be sent to DTC. If less than all of the notes within an issue are being redeemed, DTC’s practice is to determine by lot the amount of the interest of each Direct Participant in such issue to be redeemed.

Neither DTC nor Cede & Co. (nor any other DTC nominee) will consent or vote with respect to the notes unless authorized by a Direct Participant in accordance with DTC’s Procedures. Under its usual procedures, DTC mails an Omnibus Proxy to us as soon as possible after the record date. The Omnibus Proxy assigns Cede & Co.’s consenting or voting rights to those Direct Participants to whose accounts the notes are credited on the record date (identified in a listing attached to the Omnibus Proxy).

Principal and interest payments on the notes will be made to Cede & Co., or such other nominee as may be requested by an authorized representative of DTC. DTC’s practice is to credit Direct Participants’ accounts upon DTC’s receipt of funds and corresponding detail information from us or the Trustee on the payable date in accordance with their respective holdings shown on DTC’s records. Payments by Participants to Beneficial Owners will be governed by standing instructions and customary practices, as is the case with notes held for the accounts of customers in bearer form or registered in “street name”, and will be the responsibility of such Participant and not of DTC, the Trustee or us, subject to any statutory or regulatory requirements as may be in effect from time to time. Payment of principal and interest payments to Cede & Co. (or such other nominee as may be requested by an authorized representative of DTC) is our or the Trustee’s responsibility, disbursement of such payments to Direct Participants will be the responsibility of DTC, and disbursement of such payments to the Beneficial Owners will be the responsibility of Direct and Indirect Participants.

A Beneficial Owner shall give notice to elect to have its notes purchased or tendered, through its Participant, to the Tender/Remarketing Agent, and shall effect delivery of such notes by causing the Direct Participant to transfer the Participant’s interest in the notes, on DTC’s records, to the Tender/Remarketing Agent. The requirement for physical delivery of the notes in connection with an optional tender or a mandatory purchase will be deemed satisfied when the ownership rights in the notes are transferred by Direct Participants on DTC’s records and followed by a book-entry credit of tendered notes to the Tender/Remarketing Agent’s DTC account.

DTC may discontinue providing its services as depository with respect to the notes at any time by giving reasonable notice to us. Under such circumstances, in the event that a successor depository is not obtained, note certificates are required to be printed and delivered.

We may decide to discontinue use of the system of book-entry transfers through DTC (or a successor securities depository). In that event, note certificates will be printed and delivered.

The information in this section concerning DTC and DTC’s book-entry system has been obtained from sources that we believe to be reliable, but we take no responsibility for the accuracy thereof.

Note Certificates-Registration, Transfer, and Payment of Interest and Principal

If we issue note certificates, they will be registered in the name of the noteholder. The notes may be transferred or exchanged, pursuant to administrative procedures in the indenture, without the payment of any service charge (other than any tax or other governmental charge) by contacting the paying agent. Payments on note certificates will be made by check.

Interest Rate

The interest rate on the notes will either be fixed or floating. The interest paid will include interest accrued to, but excluding, the date of maturity or redemption. Interest is generally payable to the person in whose name the note is registered at the close of business on the record date before each interest payment date. Interest payable at maturity or redemption, however, will be payable to the person to whom principal is payable.

Unless an applicable pricing or prospectus supplement states otherwise, if we issue a note after a record date but on or prior to the related interest payment date, we will pay the first interest payment on the interest payment date after the next record date. We will pay interest payments by check or wire transfer, at our option.

Fixed Rate Notes

A pricing or prospectus supplement will designate the record dates, payment dates and the fixed rate of interest payable on a note. We will pay interest monthly, quarterly or semi-annually, and upon maturity or redemption. Unless an applicable pricing or prospectus supplement states otherwise, if any payment date falls on a day that is not a business day, we will pay interest on the next business day and no additional interest will be paid. Interest payments will be the amount of interest accrued to, but excluding, each payment date. Interest will be computed using a 360-day year of twelve 30-day months.

Floating Rate Notes

Each floating rate note will have an interest rate formula. The applicable pricing supplement will state the initial interest rate or interest rate formula on each note effective until the first interest reset date. The applicable pricing or prospectus supplement will state the method and dates on which the interest rate will be determined, reset and paid.

Events of Default

“Event of Default” means any of the following:

-	failure to pay the principal of (or premium, if any, on) any note of a series for three days after payment is due;

-	failure to pay any interest on any note of any series for 30 days after payment is due;

-	failure to perform any other requirements in such notes, or in the Indenture in regard to such notes, for 90 days after notice;

-	failure to pay any sinking fund installment for three days after payment is due;

-	certain events of bankruptcy or insolvency; or

-	any other event of default specified in a series of notes.

An Event of Default for a particular series of notes does not necessarily mean that an Event of Default has occurred for any other series of notes issued under the Indenture. If an Event of Default occurs and continues, the Trustee or the holders of at least 33% of the principal amount of the notes of the series affected may require us to repay the entire principal of the notes of such series within ten days after the date of such notice (“Repayment Acceleration”). In most instances, the holders of at least a majority in aggregate principal amount of the notes of the affected series may rescind a previously triggered Repayment Acceleration if we have first cured our default by depositing with the Trustee enough money to pay all (unaccelerated) past due amounts and penalties, if any.

The Trustee must within 90 days after a default occurs, notify the holders of the notes of the series of default unless such default has been cured or waived. We are required to file an annual certificate with the Trustee, signed by an officer, concerning any default by us under any provisions of the Indenture.

Subject to the provisions of the Indenture relating to its duties in case of default, the Trustee shall be under no obligation to exercise any of its rights or powers under the Indenture at the request, order or direction of any holders unless such holders offer the Trustee reasonable indemnity. Subject to the provisions for indemnification, the holders of a majority in principal amount of the notes of any series may direct the time, method and place of conducting any proceedings for any remedy available to, or exercising any trust or power conferred on, the Trustee with respect to such notes.

Modification of Indenture

Under the Indenture, our rights and obligations and the rights of the holders of any notes may be changed. Any change affecting the rights of the holders of any series of notes requires the consent of the holders of not less than a majority in aggregate principal amount of the outstanding notes of all series affected by the change, voting as one class. However, we cannot change the terms of payment of principal or interest, or a reduction in the percentage required for changes or a waiver of default, unless the holder consents. We may issue additional series of notes and take other action that does not affect the rights of holders of any series by executing supplemental indentures without the consent of any noteholders.

Consolidation, Merger or Sale

We may merge or consolidate with any entity or sell our assets substantially as an entirety as long as the successor or purchaser expressly assumes the payment of principal, and premium, if any, and interest on the notes.

Legal Defeasance

We will be discharged from our obligations on the notes of any series on the 91 ^st day after the date of the deposit referred to in the first item below if, among other things:

·	we deposit with the Trustee sufficient cash or government securities to pay (i) the principal, interest, any premium and any other sums due to the stated maturity date or a redemption date of the note of the series and (ii) any applicable mandatory sinking fund payments on the day such payments are due;
·	we deliver to the Trustee an opinion of counsel to the effect that such provision would not cause any outstanding notes then listed on a national security exchange to be delisted; and
·	we deliver to the Trustee an opinion of counsel stating that the federal income tax obligations of noteholders of that series will not change as a result of our performing the action described above.

If this happens, the noteholders of the series will not be entitled to the benefits of the Indenture except for registration of transfer and exchange of notes and replacement of lost, stolen or mutilated notes.

Covenant Defeasance

We will be discharged from our obligations under certain restrictive covenants applicable to the notes of a particular series if, among other things, we perform all of the actions described above. See Legal Defeasance . If this happens, any later breach of that particular restrictive covenant will not result in Repayment Acceleration. If we cause an Event of Default apart from breaching that restrictive covenant, there may not be sufficient money or government obligations on deposit with the Trustee to pay all amounts due on the notes of that series. In that instance, we would remain liable for such amounts.

Governing Law

The Indenture and notes of all series will be governed by the laws of the State of New York.

Concerning the Trustee

We and our affiliates use or will use some of the banking services of the Trustee and other services of its affiliates in the normal course of business.

PLAN OF DISTRIBUTION

We may sell the notes (a) through agents; (b) through underwriters or dealers; or (c) directly to one or more purchasers.

By Agents

Notes may be sold on a continuing basis through agents designated by us. The agents will agree to use their reasonable efforts to solicit purchases for the period of their appointment.

The Agents will not be obligated to make a market in the notes. We cannot predict the amount of trading or liquidity of the notes.

By Underwriters

If underwriters are used in the sale, the underwriters will acquire the notes for their own account. The underwriters may resell the notes in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the notes will be subject to certain conditions. The underwriters will be obligated to purchase all the notes of the series offered if any of the notes are purchased. Any initial public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may be changed from time to time.

Direct Sales

We may also sell notes directly. In this case, no underwriters or agents would be involved.

General Information

Underwriters, dealers, and agents that participate in the distribution of the notes may be underwriters as defined in the Securities Act of 1933 (the “Act”), and any discounts or commissions received by them from us and any profit on the resale of the notes by them may be treated as underwriting discounts and commissions under the Act.

We may have agreements with the underwriters, dealers and agents to indemnify them against certain civil liabilities, including liabilities under the Act or to contribute to payments that each underwriter, dealer or agent may be required to make in respect thereto.

Underwriters, dealers and agents and their respective affiliates may engage in transactions with, or perform services for, us or our affiliates in the ordinary course of their businesses.

LEGAL OPINIONS

Jeffrey D. Cross or Thomas G. Berkemeyer, Deputy General Counsel and Associate General Counsel, respectively, of American Electric Power Service Corporation, our service company affiliate, will issue an opinion about the legality of the notes for us. Dewey Ballantine LLP, New York, NY will issue an opinion for the agents or underwriters. From time to time, Dewey Ballantine LLP acts as counsel to our affiliates for some matters.

EXPERTS

The financial statements and the related financial statement schedule incorporated in this prospectus by reference from the Public Service Company of Oklahoma Annual Report on Form 10-K for the year ended December 31, 2005 have been audited by Deloitte & Touche llp , an independent registered public accounting firm, as stated in their reports (which reports express an unqualified opinion and , as to the report related to the financial statements, includes an explanatory paragraph concerning the adoption of new accounting pronouncements in 2003 and 2004), which are incorporated herein by reference, and have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

Table of Contents

THE COMPANY	2
PROSPECTUS SUPPLEMENTS	2
RISK FACTORS	2
WHERE YOU CAN FIND MORE INFORMATION	2
RATIO OF EARNINGS TO FIXED CHARGES	3
USE OF PROCEEDS	3	$450,000,000 Unsecured Notes
DESCRIPTION OF THE NOTES	4
General	4
Redemptions	4
Remarketed Notes	5
Book Entry Notes - Registrations, Transfer and Payment of Interest and Principal	5	PROSPECTUS
Note Certificates - Registration, Transfer, and Payment of Interest and Principal	7
Interest Rate	7
Fixed Rate Notes	8	The date of this
Floating Rate Notes	8	Prospectus is ________ __, 2006
Events of Default	8
Modification of Indenture	9
Consolidation, Merger or Sale	9
Legal Defeasance	9
Covenant Defeasance	10
Governing Law	10
Concerning the Trustee	10
PLAN OF DISTRIBUTION	10
By Agents	10
By Underwriters	10
Direct Sales	11
General Information	11
LEGAL OPINIONS	11
EXPERTS	11

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.

Other Expenses of Issuance and Distribution.*

Estimation based upon the issuance of all of the unsecured notes in two issuances:

Securities and Exchange Commission Filing Fees	$40,125
Printing Registration Statement, Prospectus, etc	30,000
Independent Registered Public Accounting Firm	80,000
Charges of Trustee (including counsel fees)	35,000
Legal fees	80,000
Rating Agency fees	265,000
Miscellaneous expenses	40,000
Total	$570,125

* Estimated, except for filing fees.

Item 15

Indemnification of Directors and Officers.

The Bylaws of the Company provide that the Company shall indemnify each person who is, was or has agreed to become a director or officer of the Company, or who has agreed to serve as a director, officer, employee or agent of the Company (or any other person or entity) at the request of the Board of Directors against all loss, liability and expenses to the fullest extent permitted by the Oklahoma General Corporation Act. Notwithstanding the foregoing, no person shall be indemnified for amounts paid in settlement unless the terms and conditions of such settlement have been consented to by the Company, and no indemnification for employees or agents shall be made without the express authorization of the Board of Directors.

Section 1031 of the Oklahoma General Corporation Act provides that an Oklahoma corporation may indemnify any persons, including officers and directors, who are, or are threatened to be made, parties to any threatened, pending or completed legal action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of such corporation), by reason of the fact that such person was an officer or director of such corporation, or is or was serving at the request of such corporation as a director, officer, employee or agent of another corporation or enterprise. The indemnity may include expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding, provided such officer or director acted in good faith and in a manner he reasonably believed to be in or not opposed to the corporation’s best interests and, for criminal proceedings, had no reasonable cause to believe that his conduct was illegal. An Oklahoma corporation may indemnify officers and directors in an action by or in the right of the corporation under the same conditions, except that no indemnification is permitted without judicial approval if the officer or director is adjudged to be liable to the corporation. Where an officer or director is successful on the merits or otherwise in the defense of any action referred to above, the corporation must indemnify him against the expenses which such officer or director actually and reasonably incurred.

The above is a general summary of certain provisions of the Company’s Bylaws and the Oklahoma General Corporation Act and is subject in all respects to the specific and detailed provisions of the Company’s Bylaws and the Oklahoma General Corporation Act.

Reference is made to the Underwriting Agreement filed as Exhibit 1 hereto, which provides for indemnification of the Company, certain of its directors and officers, and persons who control the Company, under certain circumstances.

The Company maintains insurance policies insuring its directors and officers against certain obligations that may be incurred by them.

Item 16

Exhibits.

Reference is made to the information contained in the Exhibit Index filed as part of this Registration Statement.

Item 17

Undertakings

(a)	The undersigned registrant hereby undertakes:

	(1)	To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:

		(i)	to include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

		(ii)	to reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective Registration Statement; and

		(iii)	to include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the registration statement;

		provided, however , that (i), (ii) and (iii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

	(2)	That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

	(3)	To remove from registration by means of post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

	(4)	That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

		(i)	Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

		(ii)	Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however , that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

	(5)	That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

		(i)	Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

		(ii)	Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

		(iii)	The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

		(iv)	Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b)	The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 that is incorporated by reference in this registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c)	Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable cause to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Columbus and State of Ohio, on the 26th day of April, 2006.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	Michael G. Morris*
	Chairman of the Board
	and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date

(i) Principal Executive Officer:
Michael G. Morris *	Chairman of the Board and Chief Executive Officer	April 26, 2006

(ii) Principal Financial Officer:

/s/ Susan Tomasky	Vice President	April 26, 2006
Susan Tomasky

(iii) Principal Accounting Officer:

/s/ Joseph M. Buonaiuto	Controller and Chief Accounting Officer	April 26, 2006
Joseph M. Buonaiuto

(iv) A Majority of the Directors:

Michael G. Morris*
Carl L. English*
Thomas M. Hagan*
John B. Keane*
Venita McCellon-Allen*
Robert P. Powers*
Stephen P. Smith*
Susan Tomasky
Dennis E. Welch*

* By /s/ Susan Tomasky		April 26, 2006
(Susan Tomasky, Attorney-in-Fact)

EXHIBIT INDEX

Certain of the following exhibits, designated with an asterisk (*), are filed herewith. The exhibits not so designated have heretofore been filed with the Commission and, pursuant to 17 C.F.R. Sections 201.24 and 230.411, are incorporated herein by reference to the documents indicated following the descriptions of such exhibits.

Exhibit No.	Description

*1	Copy of proposed form of Underwriting Agreement for the unsecured notes

4(a)	Copy of Indenture, dated as of November 1, 2000, between the Company and The Bank of New York, as Trustee [Registration Statement No. 333-100623, Exhibits 4(a) and 4(b); Registration Statement No. 333-100623, Exhibits 4(b) and 4(c)]

*4(b)	Copy of Fourth Supplemental Indenture, dated June 7, 2004, establishing certain terms of the Senior Notes, Series D, Due 2009

*4(c)	Copy of Fifth Supplemental Indenture, dated May 20, 2005, establishing certain terms of the Senior Notes, Series E, Due 2011

*4(d)	Copy of proposed form of Sixth Supplemental Indenture for the unsecured notes

*5	Opinion of Thomas G. Berkemeyer, Esq. regarding the validity of the notes

12	Statement re Computations of Ratios [Annual Report on Form 10-K of the Company for the year ended December 31, 2005, File No. 0-3436, Exhibit 12]

*23(a)	Consent of Deloitte & Touche LLP

23(b)	Consent of Thomas G. Berkemeyer, Esq. (included in Exhibit 5 filed herewith)

*24	Powers of Attorney and resolutions of the Board of Directors of the Company

*25	Form T-1 re eligibility of The Bank of New York to act as Trustee under the Indenture

EXHIBIT 1

PUBLIC SERVICE COMPANY OF OKLAHOMA

Underwriting Agreement

Dated ____________________

AGREEMENT made between PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation organized and existing under the laws of the State of Oklahoma (the "Company"), and the several persons, firms and corporations (the "Underwriters") named in Exhibit 1 hereto.

WITNESSETH:

WHEREAS, the Company proposes to issue and sell $__________ principal amount of its Notes to be issued pursuant to the Indenture dated as of November 1, 2000, between the Company and The Bank of New York, as trustee (the "Trustee"), as heretofore supplemented and amended and as to be further supplemented and amended (said Indenture as so supplemented being hereafter referred to as the Indenture); and

WHEREAS, the Underwriters have designated the person signing this Agreement (the Representative) to execute this Agreement on behalf of the respective Underwriters and to act for the respective Underwriters in the manner provided in this Agreement; and

WHEREAS, the Company has prepared and filed, in accordance with the provisions of the Securities Act of 1933 (the Act), with the Securities and Exchange Commission (the Commission), a registration statement and prospectus or prospectuses relating to the Notes and such registration statement has become effective; and

WHEREAS, such registration statement, as it may have been amended to the date hereof, including the financial statements, the documents incorporated or deemed incorporated therein by reference and the exhibits, being herein called the Registration Statement, and the prospectus, as included or referred to in the Registration Statement to become effective, as it may be last amended or supplemented prior to the effectiveness of the agreement (the Basic Prospectus), and the Basic Prospectus, as supplemented by a prospectus supplement which includes certain information relating to the Underwriters, the principal amount, price and terms of offering, the interest rate and redemption prices of the Notes, first filed with the Commission pursuant to the applicable paragraph of Rule 424(b) of the Commission's General Rules and Regulations under the Act (the Rules), including all documents then incorporated or deemed to have been incorporated therein by reference, being herein call the Prospectus.

NOW, THEREFORE, in consideration of the premises and the mutual covenants herein contained, it is agreed between the parties as follows:

1. Purchase and Sale : Upon the basis of the warranties and representations and on the terms and subject to the conditions herein set forth, the Company agrees to sell to the respective Underwriters named in Exhibit 1 hereto, severally and not jointly, and the respective Underwriters, severally and not jointly, agree to purchase from the Company, the respective principal amounts of the Notes set opposite their names in Exhibit 1 hereto, together aggregating all of the Notes, at a price equal to ______% of the principal amount thereof.

2. Payment and Delivery : Payment for the Notes shall be made to the Company in immediately available funds or in such other manner as the Company and the Representative shall mutually agree upon in writing, upon the delivery of the Notes to the Representative for the respective accounts of the Underwriters against receipt therefor signed by the Representative on behalf of itself and for the other Underwriters. Such delivery shall be made at 10:00 A.M., New York Time, on ____________ (or on such later business day, not more than five business days subsequent to such day, as may be mutually agreed upon by the Company and the Underwriters), unless postponed in accordance with the provisions of Section 9 hereof, at the office of Dewey Ballantine LLP, 1301 Avenue of the Americas, New York, New York 10019 , or at such other place as the Company and the Representative shall mutually agree in writing. The time at which payment and delivery are to be made is herein called the Time of Purchase.

The delivery of the Notes shall be made in fully registered form, registered in the name of CEDE & CO., to the offices of The Depository Trust Company in New York, New York and the Underwriters shall accept such delivery.

3. Conditions of Underwriters' Obligations : The several obligations of the Underwriters hereunder are subject to the accuracy of the warranties and representations on the part of the Company on the date hereof and at the Time of Purchase and to the following other conditions:

(a)	That all legal proceedings to be taken and all legal opinions to be rendered in connection with the issue and sale of the Notes shall be satisfac-tory in form and substance to Dewey Ballantine LLP, counsel to the Underwriters.

(b)	That, at the Time of Purchase, the Representative shall be furnished with the following opinions, dated the day of the Time of Purchase, with conformed copies or signed counterparts thereof for the other Underwriters, with such changes therein as may be agreed upon by the Company and the Representative with the approval of Dewey Ballantine LLP, counsel to the Underwriters

	(1)	Opinion of Jeffrey D. Cross, Esq., Thomas G. Berkemeyer, Esq. or William E. Johnson, Esq., counsel to the Company, substantially in the form heretofore previously provided to the Underwriters; and

	(2)	Opinion of Dewey Ballantine LLP, counsel to the Underwriters, substantially in the form heretofore previously provided to the Underwriters.

(c)	That the Representative shall have received on the date hereof and shall receive at the Time of Purchase letters from Deloitte & Touche LLP dated the date hereof and the day of the Time of Purchase, respectively, in form and substance satisfactory to the Representative (which may refer to the letters previously delivered to the Representative, as applicable) (i) confirming that with respect to the Company they are an independent registered public accounting firm within the meaning of the Act and the applicable published rules and regulations of the Commission thereunder, (ii) stating that in their opinion the consolidated financial statements audited by them and included or incorporated by reference in the Registration Statement, Pricing Prospectus and Prospectus, respectively, complied as to form in all material respects with the then applicable accounting requirements of the Commission, including the applicable published rules and regulations of the Commission and (iii) covering as of a date not less than three business days and not more than five business days prior to the date of each such letter, as applicable, such other matters as the Representative reasonably requests .

(d)	The pricing term sheet contemplated by Section 6(b) hereof, and any other material required pursuant to Section 433(d), shall have been filed by the Company with the Commission within the applicable time periods prescribed by Rule 433.

(e)	That no amendment to the Registration Statement and that no supplement to the Pricing Prospectus or the Prospectus of the Company (other than the Pricing Prospectus or amendments, prospectuses or prospectus supplements relating solely to securities other than the Notes) relating to the Notes and no document which would be deemed incorporated in the Pricing Prospectus or Prospectus by reference filed subsequent to the date hereof and prior to the Time of Purchase shall contain material information substantially different from that contained in the Registration Statement which is unsatisfactory in substance to the Representative or unsatisfactory in form to Dewey Ballantine LLP, counsel to the Underwriters.

(f)	That, at the Time of Purchase, appropriate orders of the Corporation Commission of Oklahoma, necessary to permit the sale of the Notes to the Underwriters, shall be in effect; and that, prior to the Time of Purchase, no stop order with respect to the effectiveness of the Registration Statement shall have been issued under the Act by the Commission or proceedings therefor initiated.

(g)	That, from the date hereof to the Time of Purchase, there shall not have been any material adverse change in the business, properties or financial condition of the Company from that set forth in the Pricing Prospectus (other than changes referred to in or contemplated by the Pricing Prospectus), and that the Company shall, at the Time of Purchase, have delivered to the Representative a certificate of an executive officer of the Company to the effect that, to the best of his knowledge, information and belief, there has been no such change.

(h)	That the Company shall have performed such of its obligations under this Agreement as are to be performed at or before the Time of Purchase by the terms hereof.

4. Certain Covenants of the Company : In further consideration of the agreements of the Underwriters herein contained, the Company covenants as follows:

	(a)	As soon as practicable, and in any event within the time prescribed by Rule 424 under the Act, to file the Prospectus with the Commission and make any other required filings pursuant to Rule 433; as soon as the Company is advised thereof, to advise the Representative and confirm the advice in writing of any request made by the Commission for amendments to the Registration Statement, Pricing Prospectus or Prospectus or for additional information with respect thereto or of the entry of an order suspending the effectiveness of the Registration Statement or preventing or suspending the use of the Pricing Prospectus or the Prospectus or of the initiation or threat of any proceedings for that purpose and, if such an order should be entered by the Commission, to make every reasonable effort to obtain the prompt lifting or removal thereof.

	(b)	To deliver to the Underwriters, without charge, as soon as practicable (and in any event within 24 hours after the date hereof), and from time to time thereafter during such period of time (not exceeding nine months) after the date hereof as they are required by law to deliver a prospectus (or required to deliver but for Rule 172 under the Act), as many copies of the Prospectus (as supplemented or amended if the Company shall have made any supplements or amendments thereto, other than supplements or amendments relating solely to securities other than the Notes) as the Representative may reasonably request; and in case any Underwriter is required to deliver a prospectus after the expiration of nine months after the date hereof, to furnish to any Underwriter, upon request, at the expense of such Underwriter, a reasonable quantity of a supplemental prospectus or of supplements to the Prospectus complying with Section 10(a)(3) of the Act.

	(c)	To furnish to the Representative a copy, certified by the Secretary or an Assistant Secretary of the Company, of the Registration Statement as initially filed with the Commission and of all amendments thereto (exclusive of exhibits), other than amendments relating solely to securities other than the Notes and, upon request, to furnish to the Representative sufficient plain copies thereof (exclusive of exhibits) for distribution to the other Underwriters.

	(d)	For such period of time (not exceeding nine months) after the date hereof as they are required by law to deliver a prospectus (or required to deliver but for Rule 172 under the Act), if any event shall have occurred as a result of which it is necessary to amend or supplement the Pricing Prospectus or the Prospectus in order to make the statements therein, in the light of the circumstances when the Pricing Prospectus or the Prospectus is delivered to a purchaser, not contain any untrue statement of a material fact or not omit to state any material fact required to be stated therein or necessary in order to make the statements therein not misleading, forthwith to prepare and furnish, at its own expense, to the Underwriters and to dealers (whose names and addresses will be furnished to the Company by the Representative) to whom principal amounts of the Notes may have been sold by the Representative for the accounts of the Underwriters and, upon request, to any other dealers making such request, copies of such amendments to the Pricing Prospectus or the Prospectus or supplements to the Pricing Prospectus or the Prospectus.

	(e)	As soon as practicable, the Company will make generally available to its security holders and to the Underwriters an earnings statement or statement of the Company and its subsidiaries which will satisfy the provisions of Section 11(a) of the Act and Rule 158 under the Act.

	(f)	To use its best efforts to qualify the Notes for offer and sale under the securities or "blue sky" laws of such jurisdictions as the Representative may designate within six months after the date hereof and itself to pay, or to reimburse the Underwriters and their counsel for, reasonable filing fees and expenses in connection therewith in an amount not exceeding $3,500 in the aggregate (including filing fees and expenses paid and incurred prior to the effective date hereof), provided, however, that the Company shall not be required to qualify as a foreign corporation or to file a consent to service of process or to file annual reports or to comply with any other requirements deemed by the Company to be unduly burdensome.

	(g)	To pay all expenses, fees and taxes (other than transfer taxes on resales of the Notes by the respective Underwriters) in connection with the issuance and delivery of the Notes, except that the Company shall be required to pay the fees and disbursements (other than disbursements referred to in paragraph (f) of this Section 4) of counsel to the Underwriters, only in the events provided in paragraph (h) of this Section 4 and paragraph (a) of Section 8, the Underwriters hereby agreeing to pay such fees and disbursements in any other event.

	(h)	If the Underwriters shall not take up and pay for the Notes due to the failure of the Company to comply with any of the conditions specified in Section 3 hereof, or, if this Agreement shall be terminated in accordance with the provisions of Section 9 or 10 hereof, to pay the fees and disbursements of counsel to the Underwriters, and, if the Underwriters shall not take up and pay for the Notes due to the failure of the Company to comply with any of the conditions specified in Section 3 hereof, to reimburse the Underwriters for their reasonable out-of-pocket expenses, in an aggregate amount not exceeding a total of $10,000, incurred in connection with the financing contemplated by this Agreement.

	(i)	During the period from the date hereof and continuing to and including the earlier of (i) the date which is after the Time of Purchase on which the distribution of the Notes ceases, as determined by the Representative in its sole discretion, and (ii) the date which is 30 days after the Time of Purchase, the Company agrees not to offer, sell, contract to sell or otherwise dispose of any Notes of the Company or any substantially similar securities of the Company without the consent of the Representative.

5. Warranties of the Company : The Company represents and warrants to, and agrees with you, as set forth below:

	(a)	the Registration Statement on its effective date complied with the applicable provisions of the Act and the rules and regulations of the Commission and the Registration Statement at its effective date and as of the Applicable Time did not, and at the Time of Purchase will not, contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, the Pricing Disclosure Package as of the Applicable Time did not contain an untrue statement of a material fact necessary or omit to state a material fact necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading, and the Basic Prospectus on the date of this Agreement and the Prospectus as of its date complies, and at the Time of Purchase the Prospectus will comply, with the applicable provisions of the Act and the Trust Indenture Act of 1939, as amended (Trust Indenture Act), and the rules and regulations of the Commission, the Basic Prospectus on the date of this Agreement and the Prospectus when first filed in accordance with Rule 424(b) under the Act do not, and the Prospectus at the Time of Purchase will not, contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, except that the Company makes no warranty or representation to the Underwriters with respect to any statements or omissions made in the Registration Statement, the Basic Prospectus, any Permitted Free Writing Prospectus or the Prospectus in reliance upon and in conformity with information furnished in writing to the Company by, or through the Representative on behalf of, any Underwriter expressly for use in the Registration Statement, the Basic Prospectus or Prospectus, or to any statements in or omissions from that part of the Registration Statement that shall constitute the Statement of Eligibility under the Trust Indenture Act of any indenture trustee under an indenture of the Company.

	(b)	As of the Time of Purchase, the Indenture will have been duly authorized by the Company and duly qualified under the Trust Indenture Act and, when executed and delivered by the Trustee and the Company, will constitute a legal, valid and binding instrument enforceable against the Company in accordance with its terms and such Notes will have been duly authorized, executed, authenticated and, when paid for by the purchasers thereof, will constitute legal, valid and binding obligations of the Company entitled to the benefits of the Indenture, except as the enforceability thereof may be limited by bankruptcy, insolvency, or other similar laws affecting the enforcement of creditors' rights in general, and except as the availability of the remedy of specific performance is subject to general principles of equity (regardless of whether such remedy is sought in a proceeding in equity or at law), and by an implied covenant of good faith and fair dealing.

	(c)	The documents incorporated by reference in the Registration Statement or Pricing Prospectus, when they were filed with the Commission, complied in all material respects with the applicable provisions of the Securities Exchange Act of 1934, as amended and the rules and regulations of the Commission thereunder, and as of such time of filing, when read together with the Pricing Prospectus, the Permitted Free Writing Prospectuses and the Prospectus, none of such documents contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading. The information contained in a Permitted Free Writing Prospectus listed in Exhibit 3 does not conflict with the information contained in the Registration Statement, the Pricing Prospectus or the Prospectus and no such Permitted Free Writing Prospectus, taken together with the remainder of the Pricing Disclosure Package as of the Applicable Time, did contain an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading.

	(d)	Since the respective dates as of which information is given in the Registration Statement and the Pricing Prospectus, except as otherwise referred to or contemplated therein, there has been no material adverse change in the business, properties or financial condition of the Company.

	(e)	This Agreement has been duly authorized, executed and delivered by the Company.

	(f)	The consummation by the Company of the transactions contemplated herein is not in violation of its charter or bylaws, will not result in the violation of any applicable law, statute, rule, regulation, judgment, order, writ or decree of any government, government instrumentality or court having jurisdiction over the Company or its properties, and will not conflict with, or result in a breach of any of the terms or provisions of, or constitute a default under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company under any contract, indenture, mortgage, loan agreement, note, lease or other agreement or instrument to which the Company is a party or by which it may be bound or to which any of its properties may be subject (except for conflicts, breaches or defaults which would not, individually or in the aggregate, be materially adverse to the Company or materially adverse to the transactions contemplated by this Agreement).

	(g)	No authorization, approval, consent or order of any court or governmental authority or agency is necessary in connection with the issuance and sale by the Company of the Notes or the transactions by the Company contemplated in this Agreement, except (A) such as may be required under the 1933 Act or the rules and regulations thereunder; (B) the qualification of the Indenture under the Trust Indenture Act; (C) the approval of the Corporation commission of Oklahoma; and (D) such consents, approvals, authorizations, registrations or qualifications as may be required under state securities or “Blue Sky” laws.

	(h)	The consolidated financial statements of the Company and its consolidated subsidiaries together with the notes thereto, included or incorporated by reference in the Pricing Prospectus and the Prospectus present fairly the financial position of the Company at the dates or for the periods indicated; said consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles applied, apart from reclassifications disclosed therein, on a consistent basis throughout the periods involved; and the selected consolidated financial information of the Company included in the Pricing Prospectus and the Prospectus presents fairly the information shown therein and has been compiled, apart from reclassifications disclosed therein, on a basis consistent with that of the audited financial statements of the Company included or incorporated by reference in the Pricing Prospectus and the Prospectus.

	(i)	There is no pending action, suit, investigation, litigation or proceeding, including, without limitation, any environmental action, affecting the Company before any court, governmental agency or arbitration that is reasonably likely to have a material adverse effect on the business, properties, financial condition or results of operations of the Company, except as disclosed in the Pricing Prospectus

	(j)	At the determination date for purposes of the Notes within the meaning of Rule 164(h) under the Act, the Company was not an “ineligible issuer” as defined in Rule 405 under the Act.

	(k)	The Company has not made any filings pursuant to the Securities Exchange Act of 1934, as amended, or the rules and regulations thereunder, within 24 hours preceding the Applicable Time.

The Company's covenants, warranties and representations contained in this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of any person, and shall survive the delivery of and payment for the Notes hereunder.

6. Free Writing Prospectuses :

	(a)	The Company represents and agrees that, without the prior consent of the Representative, it has not made and will not make any offer relating to the Notes that would constitute a “free writing prospectus” as defined in Rule 405 under the Act, other than a Permitted Free Writing Prospectus; each Underwriter, severally and not jointly, represents and agrees that, without the prior consent of the Company and the Representative, it has not made and will not make any offer relating to the Notes that would constitute a “free writing prospectus,” as defined in Rule 405 under the Act, other than a Permitted Free Writing Prospectus or one or more free writing prospectuses that contain s only preliminary or final terms of the Notes and is not required to be filed by the Company pursuant to Rule 433 (an “Underwriter Free Writing Prospectus”); any such free writing prospectus the use of which has been consented to by the Company and the Representative (which shall include the pricing term sheet discussed in Section 6(b)) is listed in Exhibit 3 and herein called a “Permitted Free Writing Prospectus.”

	(b)	The Company agrees to prepare a pricing term sheet, substantially in the form of Exhibit 2 hereto and approved by the Representative, and to file such pricing term sheet pursuant to Rule 433(d) under the Securities Act within the time period prescribed by such Rule.

	(c)	The Company and each Underwriter has complied and will comply with the requirements of Rule 433 applicable to any other Permitted Free Writing Prospectus, including timely Commission filing where required and legending.

	(d)	The Company and each Underwriter agrees that if at any time following issuance of a Permitted Free Writing Prospectus any event occurred or occurs as a result of which such Permitted Free Writing Prospectus would conflict in any material respect with the information in the Registration Statement, the Pricing Prospectus or the Prospectus or include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in light of the circumstances then prevailing, not misleading, then (i) the party that first becomes aware of the foregoing will give prompt notice thereof to the Representative and/ or the Company, as applicable, and, (ii) if requested by the Representative or the Company, as applicable, the Company will prepare and furnish without charge a Permitted Free Writing Prospectus or other document which will correct such conflict, statement or omission.

	(e)	Each Underwriter agrees that (i) no information that is conveyed to investors has been or will be inconsistent with the information contained in the Pricing Disclosure Package, and (ii) if an Underwriter shall use an Underwriter Free Writing Prospectus , the liability arising from its use shall be the sole responsibility of the Underwriter using such Underwriter Free Writing Prospectus; provided, however, that, for the avoidance of doubt, this clause 6(e)(ii) shall not be interpreted as tantamount to the indemnification obligations contained in Section 8(b) hereof .

7. Warranties of Underwriters : Each Underwriter warrants and represents that the information furnished in writing to the Company through the Representative for use in the Registration Statement, in the Basic Prospectus, in any Permitted Free Writing Prospectus, in the Pricing Prospectus, in the Prospectus, or in the Prospectus as amended or supplemented is correct as to such Underwriter. The warranties and representations of such Underwriter contained in this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of the Company or other person, and shall survive the delivery of and payment for the Notes hereunder.

8. Indemnification and Contribution :

	(a)	To the extent permitted by law, the Company agrees to indemnify and hold you harmless, your officers and directors and each person, if any, who controls you within the meaning of Section 15 of the Act, against any and all losses, claims, damages or liabilities, joint or several, to which you, they or any of you or them may become subject under the Act or otherwise, and to reimburse you and such controlling person or persons, if any, for any legal or other expenses incurred by you or them in connection with defending any action, insofar as such losses, claims, damages, liabilities or actions arise out of or are based upon any alleged untrue statement or untrue statement of a material fact contained in the Registration Statement, in the Basic Prospectus (if used prior to the effective date of this Agreement), in the Pricing Prospectus, in any Permitted Free Writing Prospectus, in any “issuer free writing prospectus” (as defined in Rule 433 under the Act) or in the Prospectus, or if the Company shall furnish or cause to be furnished to you any amendments or any supplements to the Pricing Prospectus or the Prospectus, in the Pricing Prospectus or the Prospectus as so amended or supplemented except to the extent that such amendments or supplements relate solely to securities other than the Notes (provided that if such Prospectus or such Prospectus, as amended or supplemented, is used after the period of time referred to in Section 4(b) hereof, it shall contain such amendments or supplements as the Company deems necessary to comply with Section 10(a) of the Act), or arise out of or are based upon any alleged omission or omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as such losses, claims, damages, liabilities or actions arise out of or are based upon any such alleged untrue statement or omission, or untrue statement or omission which was made in the Registration Statement, in the Basic Prospectus, in the Pricing Prospectus, in any Permitted Free Writing Prospectus, in any “issuer free writing prospectus” (as defined in Rule 433 under the Act) or in the Prospectus, or in the Prospectus as so amended or supplemented, in reliance upon and in conformity with information furnished in writing to the Company by or through the Representative expressly for use therein or with any statements in or omissions from that part of the Registration Statement that shall constitute the Statement of Eligibility under the Trust Indenture Act of any indenture trustee under an indenture of the Company. You agree promptly after the receipt by you of written notice of the commencement of any action in respect to which indemnity from the Company on account of its agreement contained in this Section 8(a) may be sought by you, or by any person controlling you, to notify the Company in writing of the commencement thereof, but your omission so to notify the Company of any such action shall not release the Company from any liability which it may have to you or to such controlling person otherwise than on account of the indemnity agreement contained in this Section 8(a). In case any such action shall be brought against you or any such person controlling you and you shall notify the Company of the commencement thereof, as above provided, the Company shall be entitled to participate in, and, to the extent that it shall wish, including the selection of counsel (such counsel to be reasonably acceptable to the indemnified party), to direct the defense thereof at its own expense. In case the Company elects to direct such defense and select such counsel (hereinafter, Company's counsel), you or any controlling person shall have the right to employ your own counsel, but, in any such case, the fees and expenses of such counsel shall be at your expense unless (i) the Company has agreed in writing to pay such fees and expenses or (ii) the named parties to any such action (including any impleaded parties) include both you or any controlling person and the Company and you or any controlling person shall have been advised by your counsel that a conflict of interest between the Company and you or any controlling person may arise (and the Company’s counsel shall have concurred in good faith with such advice) and for this reason it is not desirable for the Company’s counsel to represent both the indemnifying party and the indemnified party (it being understood, however, that the Company shall not, in connection with any one such action or separate but substantially similar or related actions in the same jurisdiction arising out of the same general allegations or circumstances, be liable for the reasonable fees and expenses of more than one separate firm of attorneys for you or any controlling person (plus any local counsel retained by you or any controlling person in their reasonable judgment), which firm (or firms) shall be designated in writing by you or any controlling person).

	(b)	Each Underwriter agrees, to the extent permitted by law, severally and not jointly, to indemnify, hold harmless and reimburse the Company, its directors and such of its officers as shall have signed the Registration Statement, and each person, if any, who controls the Company within the meaning of Section 15 of the Act, to the same extent and upon the same terms as the indemnity agreement of the Company set forth in Section 8(a) hereof, but only with respect to untrue statements or alleged untrue statements or omissions or alleged omissions made in the Registration Statement, or in the Basic Prospectus, or in the Pricing Prospectus, or in any Permitted Free Writing Prospectus, or in the Prospectus, or in the Prospectus as so amended or supplemented, in reliance upon and in conformity with information furnished in writing to the Company by the Representative on behalf of such Underwriter expressly for use therein. The Company agrees promptly after the receipt by it of written notice of the commencement of any action in respect to which indemnity from you on account of your agreement contained in this Section 8(b) may be sought by the Company, or by any person controlling the Company, to notify you in writing of the commencement thereof, but the Company's omission so to notify you of any such action shall not release you from any liability which you may have to the Company or to such controlling person otherwise than on account of the indemnity agreement contained in this Section 8(b).

	(c)	If recovery is not available or insufficient under Section 8(a) or 8(b) hereof for any reason other than as specified therein, the indemnified party shall be entitled to contribution for any and all losses, claims, damages, liabilities and expenses for which such indemnification is so unavailable or insufficient under this Section 8(c). In determining the amount of contribution to which such indemnified party is entitled, there shall be considered the portion of the proceeds of the offering of the Notes realized by the Company on the one hand and the Underwriters on the other hand, the relative knowledge and access to information concerning the matter with respect to which the claim was asserted, the opportunity to correct and prevent any statement or omission, and any equitable considerations appropriate under the circumstances. The Company and the Underwriters agree that it would not be equitable if the amount of such contribution were determined by pro rata or per capita allocation (even if the Underwriters were treated as one entity for such purpose) without reference to the considerations called for in the previous sentence. No Underwriter or any person controlling such Underwriter shall be obligated to contribute any amount or amounts hereunder which in the aggregate exceeds the total price of the Notes purchased by such Underwriter under this Agreement, less the aggregate amount of any damages which such Underwriter and its controlling persons have otherwise been required to pay in respect of the same claim or any substantially similar claim. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. An Underwriter’s obligation to contribute under this Section 8 is in proportion to its purchase obligation and not joint with any other Underwriter.

	(d)	No indemnifying party shall, without the prior written consent of the indemnified parties, settle or compromise or consent to the entry of any judgment with respect to any litigation, or any investigation or proceeding by any governmental agency or body, commenced or threatened, or any claim whatsoever in respect of which indemnification or contribution could be sought under this Section 8 (whether or not the indemnified parties are actual or potential parties thereto), unless such settlement, compromise or consent (i) includes an unconditional release of each indemnified party from all liability arising out of such litigation, investigation, proceeding or claim and (ii) does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of such indemnified party.

	(e)	In no event shall any indemnifying party have any liability or responsibility in respect of the settlement or compromise of, or consent to the entry of any judgment with respect to, any pending or threatened action or claim effected without its prior written consent.

The agreements contained in this Section 8 hereof shall remain in full force and effect regardless of any investigation made by or on behalf of any person, and shall survive the delivery of and payment for the Notes hereunder.

9. Default of Underwriters : If any Underwriter under this Agreement shall fail or refuse (otherwise than for some reason sufficient to justify, in accordance with the terms hereof, the cancellation or termination of its obligations hereunder) to purchase and pay for the principal amount of Notes which it has agreed to purchase and pay for hereunder, and the aggregate principal amount of Notes which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate principal amount of the Notes, the other Underwriters shall be obligated severally in the proportions which the amounts of Notes set forth opposite their names in Exhibit 1 hereto bear to the aggregate principal amount of Notes set forth opposite the names of all such non-defaulting Underwriters, to purchase the Notes which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on the terms set forth herein; provided that in no event shall the principal amount of Notes which any Underwriter has agreed to purchase pursuant to Section 1 hereof be increased pursuant to this Section 9 by an amount in excess of one-ninth of such principal amount of Notes without the written consent of such Underwriter. If any Underwriter or Underwriters shall fail or refuse to purchase Notes and the aggregate principal amount of Notes with respect to which such default occurs is more than one-tenth of the aggregate principal amount of the Notes then this Agreement shall terminate without liability on the part of any non-defaulting Underwriter; provided, however, that the non-defaulting Underwriters may agree, in their sole discretion, to purchase the Notes which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on the terms set forth herein. In the event of any such termination, the Company shall not be under any liability to any Underwriter (except to the extent, if any, provided in Section 4(h) hereof), nor shall any Underwriter (other than an Underwriter who shall have failed or refused to purchase the Notes without some reason sufficient to justify, in accordance with the terms hereof, its termination of its obligations hereunder) be under any liability to the Company or any other Underwriter.

Nothing herein contained shall release any defaulting Underwriter from its liability to the Company or any non-defaulting Underwriter for damages occasioned by its default hereunder.

10. Termination of Agreement by the Underwriters : This Agreement may be terminated at any time prior to the Time of Purchase by the Representative if, after the execution and delivery of this Agreement and prior to the Time of Purchase, in the Representative's reasonable judgment, the Underwriters' ability to market the Notes shall have been materially adversely affected because:

		(i)	trading in securities on the New York Stock Exchange shall have been generally suspended by the Commission or by the New York Stock Exchange or trading in the securities of the Company shall have been suspended by the New York Stock Exchange, or

		(ii)	there shall have occurred any outbreak or escalation of hostilities, declaration by the United States of a national emergency or war or other national or international calamity or crisis, or

		(iii)	a general banking moratorium shall have been declared by Federal or New York State authorities, or

		(iv)	there shall have been any decrease in the ratings of the Company's debt securities by Moody's Investors Services, Inc. (Moody's) or Standard & Poor's Ratings Group (S&P) or either Moody's or S&P shall publicly announce that it has such debt securities under consideration for possible further downgrade.

If the Representative elects to terminate this Agreement, as provided in this Section 10, the Representative will promptly notify the Company by telephone or by telex or facsimile transmission, confirmed in writing. If this Agreement shall not be carried out by any Underwriter for any reason permitted hereunder, or if the sale of the Notes to the Underwriters as herein contemplated shall not be carried out because the Company is not able to comply with the terms hereof, the Company shall not be under any obligation under this Agreement and shall not be liable to any Underwriter or to any member of any selling group for the loss of anticipated profits from the transactions contemplated by this Agreement (except that the Company shall remain liable to the extent provided in Section 4(h) hereof) and the Underwriters shall be under no liability to the Company nor be under any liability under this Agreement to one another.

11. Notices : All notices hereunder shall, unless otherwise expressly provided, be in writing and be delivered at or mailed to the following addresses or by telex or facsimile transmission confirmed in writing to the following addresses: if to the Underwriters, to __________________________________________________________________ and, if to the Company, to Public Service Company of Oklahoma, c/o American Electric Power Service Corporation, 1 Riverside Plaza, Columbus, Ohio 43215, Attention: General Counsel (fax 614/716-1687).

12. Parties in Interest : The agreement herein set forth has been and is made solely for the benefit of the Underwriters, the Company (including the directors thereof and such of the officers thereof as shall have signed the Registration Statement), the controlling persons, if any, referred to in Section 8 hereof, and their respective successors, assigns, executors and administrators, and, except as expressly otherwise provided in Section 9 hereof, no other person shall acquire or have any right under or by the virtue of this Agreement. The Company acknowledges and agrees that in connection with all aspects of each transaction contemplated by this Underwriting Agreement, the Company and the Underwriters have an arms length business relationship that creates no fiduciary duty on the part of any party and each expressly disclaims any fiduciary relationship.

13. Definition of Certain Terms : If there be two or more persons, firms or corporations named in Exhibit 1 hereto, the term "Underwriters", as used herein, shall be deemed to mean the several persons, firms or corporations, so named (including the Representative herein mentioned, if so named) and any party or parties substituted pursuant to Section 9 hereof, and the term "Representative", as used herein, shall be deemed to mean the representative or representatives designated by, or in the manner authorized by, the Underwriters. All obligations of the Underwriters hereunder are several and not joint. If there shall be only one person, firm or corporation named in Exhibit 1 hereto, the term "Underwriters" and the term "Representative", as used herein, shall mean such person, firm or corporation. The term "successors" as used in this Agreement shall not include any purchaser, as such purchaser, of any of the Notes from any of the respective Underwriters.

14. Conditions of the Company's Obligations : The obligations of the Company hereunder are subject to the Underwriters' performance of their obligations hereunder, and the further condition that at the Time of Purchase the Commission shall have issued appropriate orders, and such orders shall remain in full force and effect, authorizing the transactions contemplated hereby.

15. Applicable Law : This Agreement will be governed and construed in accordance with the laws of the State of New York.

16. Execution of Counterparts : This Agreement may be executed in several counterparts, each of which shall be regarded as an original and all of which shall constitute one and the same document.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed by their respective officers thereunto duly authorized, on the date first above written.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:	/s/
		Name:
		Title: Vice President

___________________________

as Representative

and on behalf of the Underwriters

named in Exhibit 1 hereto

EXHIBIT 4(b)

PUBLIC SERVICE COMPANY OF OKLAHOMA

and

THE BANK OF NEW YORK,

AS TRUSTEE

___________________

FOURTH SUPPLEMENTAL INDENTURE

Dated as of June 7, 2004

Supplemental to the Indenture

dated as of November 1, 2000

4.70% Senior Notes, Series D, due 2009

FOURTH SUPPLEMENTAL INDENTURE, dated as of June 7, 2004, between PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the “Company”), and THE BANK OF NEW YORK, a New York banking corporation organized and existing under the laws of the State of New York, as Trustee under the Original Indenture referred to below (the “Trustee”).

RECITALS OF THE COMPANY

The Company has heretofore executed and delivered to the Trustee an indenture dated as of November 1, 2000 (the “Original Indenture”), to provide for the issuance from time to time of its debentures, notes or other evidences of indebtedness (the “Senior Notes”), the form and terms of which are to be established as set forth in Section 201 and 301 of the Original Indenture.

Section 901 of the Original Indenture provides, among other things, that the Company and the Trustee may enter into indentures supplemental to the Original Indenture for, among other things, the purpose of establishing the form and terms of the Senior Notes of any series as permitted in Sections 201 and 301 of the Original Indenture.

The Company desires to create a series of the Senior Notes in an aggregate principal amount of $50,000,000 to be designated the “4.70% Senior Notes, Series D, due 2009” (the “4.70% Senior Notes”), and all action on the part of the Company necessary to authorize the issuance of the 4.70% Senior Notes under the Original Indenture and this Fourth Supplemental Indenture has been duly taken.

All acts and things necessary to make the 4.70% Senior Notes, when executed by the Company and completed, authenticated and delivered by the Trustee as provided in the Original Indenture and this Fourth Supplemental Indenture, the valid and binding obligations of the Company and to constitute these presents a valid and binding supplemental indenture and agreement according to its terms, have been done and performed.

NOW, THEREFORE, THIS FOURTH SUPPLEMENTAL INDENTURE WITNESSETH:

That in consideration of the premises and of the acceptance and purchase of the 4.70% Senior Notes by the Holders thereof and of the acceptance of this trust by the Trustee, the Company covenants and agrees with the Trustee, for the equal benefit of the Holders of the 4.70% Senior Notes, as follows:

ARTICLE ONE

Definitions

The use of the terms and expressions herein is in accordance with the definitions, uses and constructions contained in the Original Indenture and the form of the Global Security attached hereto as Exhibit A .

ARTICLE TWO

Terms and Issuance of the 4.70% Senior Notes

SECTION 201. Issue of 4.70% Senior Notes

A series of Senior Notes which shall be designated the “4.70% Senior Notes, Series D, due 2009” shall be executed, authenticated and delivered from time to time in accordance with the provisions of, and shall in all respects be subject to, the terms, conditions and covenants of, the Original Indenture and this Fourth Supplemental Indenture (including the form of Global Security set forth in Exhibit A hereto). The aggregate principal amount of the 4.70% Senior Notes, which may be authenticated and delivered under this Fourth Supplemental Indenture shall not, except as permitted by the provisions of the Original Indenture, exceed $50,000,000.

SECTION 202. Form of 4.70% Senior Notes, Incorporation of Terms

The 4.70% Senior Notes shall be substantially in the form of the Global Security attached hereto as Exhibit A . The terms of such 4.70% Senior Notes are herein incorporated by reference and are part of this Fourth Supplemental Indenture.

SECTION 203. Depositary for Global Securities

The Depositary for any Global Securities of the series of which this 4.70% Senior Note is a part shall be The Depository Trust Company in The City of New York.

SECTION 204. Restrictions on Liens

The covenant contained in Section 1007 of the Original Indenture shall not be applicable to the 4.70% Senior Notes.

So long as any of the 4.70% Senior Notes are outstanding, the Company will not create or suffer to be created or to exist any additional mortgage, pledge, security interest, or other lien (collectively “Liens”) on any of its utility properties or tangible assets now owned or hereafter acquired to secure any indebtedness for borrowed money (“Secured Debt”), without providing that the 4.70% Senior Notes will be similarly secured. This restriction does not apply to the Company’s subsidiaries, nor will it prevent any of them from creating or permitting to exist Liens on their property or assets to secure any Secured Debt. Further, this restriction on Secured Debt does not apply to the Company’s existing first mortgage bonds that have previously been issued under its Mortgage and Deed of Trust, dated July 1, 1945, between the Company and Liberty Bank and Trust Company of Tulsa, National Association, as successor to The First National Bank and Trust Company of Tulsa, as Trustee or any indenture supplemental thereto; provided that this restriction will apply to future issuances thereunder (other than issuances of refunding first mortgage bonds). In addition, this restriction does not prevent the creation or existence of:

(a) Liens on property existing at the time of acquisition or construction of such property (or created within one year after completion of such acquisition or construction), whether by purchase, merger, construction or otherwise, or to secure the payment of all or any part of the purchase price or construction cost thereof, including the extension of any Liens to repairs, renewals, replacements, substitutions, betterments, additions, extensions and improvements then or thereafter made on the property subject thereto;

(b) Financing of the Company’s accounts receivable for electric service;

(c) Any extensions, renewals or replacements (or successive extensions, renewals or replacements), in whole or in part, of liens permitted by the foregoing clauses; and

(d) The pledge of any bonds or other securities at any time issued under any of the Secured Debt permitted by the above clauses.

In addition to the permitted issuances above, Secured Debt not otherwise so permitted may be issued in an amount that does not exceed 15% of Net Tangible Assets as defined below.

“Net Tangible Assets” means the total of all assets (including revaluations thereof as a result of commercial appraisals, price level restatement or otherwise) appearing on the Company’s balance sheet, net of applicable reserves and deductions, but excluding goodwill, trade names, trademarks, patents, unamortized debt discount and all other like intangible assets (which term shall not be construed to include such revaluations), less the aggregate of the Company’s current liabilities appearing on such balance sheet. For purposes of this definition, the Company’s balance sheet does not include assets and liabilities of its subsidiaries.

This restriction also does not apply to or prevent the creation or existence of leases made, or existing on property acquired, in the ordinary course of business.

SECTION 205. Place of Payment

The Place of Payment in respect of the 4.70% Senior Notes will be at the principal office or place of business of the Trustee or its successor in trust under the Indenture, which, at the date hereof, is located at 101 Barclay Street, New York, NY 10281, Attention: Corporate Trust Department.

SECTION 206. Sinking Funds .

Article Twelve of the Indenture shall not apply to the 4.70% Senior Notes.

SECTION 207. Redemption

The 4.70% Senior Notes shall be redeemable at the option of the Company, in whole at any time or in part from time to time, upon not less than thirty but not more than sixty days’ previous notice given by mail to the registered owners of the 4.70% Senior Notes at a redemption price equal to the greater of (i) 100% of the principal amount of the 4.70% Senior Notes being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the 4.70% Senior Notes being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 20 basis points, plus, in each case, accrued interest thereon to the date of redemption.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the 4.70% Senior Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes.

“Comparable Treasury Price” means, with respect to any redemption date, (i) the average of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) on the third Business Day preceding such redemption date, as set forth in the daily statistical release (or any successor release) published by the Federal Reserve Bank of New York and designated “Composite 3:30 p.m. Quotations for U. S. Government Securities” or (ii) if such release (or any successor release) is not published or does not contain such prices on such third Business Day, the Reference Treasury Dealer Quotation for such redemption date.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer” means a primary U.S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer Quotation” means, with respect to the Reference Treasury Dealer and any redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the third Business Day preceding such redemption date.

“Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date.

ARTICLE THREE

Miscellaneous

SECTION 301. Execution as Supplemental Indenture

This Fourth Supplemental Indenture is executed and shall be construed as an indenture supplemental to the Original Indenture and, as provided in the Original Indenture, this Fourth Supplemental Indenture forms a part thereof.

SECTION 302. Conflict with Trust Indenture Act

If any provision hereof limits, qualifies or conflicts with another provision hereof which is required to be included in this Fourth Supplemental Indenture by any of the provisions of the Trust Indenture Act, such required provision shall control.

SECTION 303. Effect of Headings

The Article and Section headings herein are for convenience only and shall not affect the construction hereof.

SECTION 304. Successors and Assigns

All covenants and agreements by the Company in this Fourth Supplemental Indenture shall bind its successors and assigns, whether so expressed or not.

SECTION 305. Separability Clause

In case any provision in this Fourth Supplemental Indenture or in the 4.70% Senior Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 306. Benefits of Fourth Supplemental Indenture

Nothing in this Fourth Supplemental Indenture or in the 4.70% Senior Notes, express or implied, shall give to any Person, other than the parties hereto and their successors hereunder and the Holders, any benefit or any legal or equitable right, remedy or claim under this Fourth Supplemental Indenture.

SECTION 307. Execution and Counterparts

This Fourth Supplemental Indenture may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, the parties hereto have caused this Fourth Supplemental Indenture to be duly executed and attested, all as of the day and year first above written.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:	/s/ /s/ Stephen P. Smith
		Name: Stephen P. Smith
		Title: Treasurer
Attest:
/s/ Thomas G. Berkemeyer
Assistant Secretary

		THE BANK OF NEW YORK,
		as Trustee

	By:	/s/ Van K. Brown
		Authorized Signatory
Attest:

/s/Michael Pitfick
Name: Michael Pitfick
Title: Assistant Vice President

STATE OF OHIO	)
	)	: ss
COUNTY OF FRANKLIN	)

On the 4th day of June, 2004, personally appeared before me, a Notary Public within and for said County in the State of Ohio, Stephen P. Smith and Thomas G. Berkemeyer, to me known and known to me to be respectively the Treasurer and Assistant Secretary of Public Service Company of Oklahoma, one of the corporations named in and which executed the foregoing instrument, who severally acknowledged that they did sign said instrument as such Treasurer and Assistant Secretary for and on behalf of said corporation and that the same is their free act and deed as such Treasurer and Assistant Secretary, respectively, and the free and corporate act and deed of said corporation.

In witness whereof, I have hereunto set my hand notarial seal this 4th day of June, 2004.

	/s/ Mary M. Soltesz
	My Commission expires 7-13-04

STATE OF NEW YORK	)
	)	: ss
COUNTY OF NEW YORK	)

On the 7th day of June, 2004, personally appeared before me, a Notary Public within and for said County in the State of New York, Van K. Brown and Michael Pitfick, to me known and known to me to be respectively the Vice President and Assistant Vice President of The Bank of New York, one of the corporations named in and which executed the foregoing instrument, who severally acknowledged that they did sign said instrument as such Vice President and Assistant Vice President for and on behalf of said corporation and that the same is their free act and deed as such Vice President and Assistant Vice President, respectively, and the free and corporate act and deed of said corporation.

In witness whereof, I have hereunto set my hand notarial seal this 7th day of June, 2004.

	/s/ William J. Cassels
	Notary Public, State of New York
	No.01CA5037739 Commission Expires 5-18-06

EXHIBIT A to EXHIBIT 4(b)

THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE OF A DEPOSITARY. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE, AND NO TRANSFER OF THIS SECURITY (OTHER THAN A TRANSFER OF THIS SECURITY AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED CIRCUMSTANCES.

Unless this certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to Public Service Company of Oklahoma or its agent for registration of transfer, exchange or payment, and any definitive certificate issued is registered in the name of Cede & Co. or in such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL in as much as the registered owner hereof, Cede & Co., has an interest herein.

No. R-1

PUBLIC SERVICE COMPANY OF OKLAHOMA

4.70% Senior Notes, Series D, due 2009

CUSIP No. 744533BF6

$50,000,000

PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the “Company”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to CEDE & CO. or registered assigns, the principal sum of FIFTY MILLION DOLLARS ($50,000,000) on June 15, 2009 (the “Final Maturity”), and to pay interest thereon from June 7, 2004 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on June 15 and December 15 each year, commencing December 15, 2004, at the interest rate per annum specified above, until the principal amount shall have been paid or duly provided for. Interest shall be computed on the basis of a 360-day year of twelve 30-day months.

The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the May 31 or November 30 (whether or not a Business Day) immediately preceding the Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture.

Payment of the principal of (and premium, if any) and interest on this Security will be made at the office or agency of the Company maintained for that purpose in the Borough of Manhattan, The City of New York, New York, in such coin or currency of the United States of America as at the time of payment is legal tender for the payment of public and private debts; provided, however, that at the option of the Company payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register.

This Security has initially been issued in the form of a Global Security, and the Company has initially designated The Depository Trust Company (the “Depositary”, which term shall include any successor depositary) as the depositary for this Security. For as long as this Security or any portion hereof is issued in such form, and notwithstanding the previous paragraph, all payments of interest, principal and other amounts in respect of this Security or portion thereof shall be made to the Depositary or its nominee in accordance with the Applicable Procedures in the coin or currency specified above and as further provided herein.

This Security is one of a duly authorized issue of securities of the Company (the “Securities”), issued and to be issued in one or more series under an Indenture, dated as of November 1, 2000, as amended and supplemented from time to time (the “Indenture”, which term shall have the meaning assigned to it in such instrument), between the Company and The Bank of New York, a New York banking corporation, as Trustee (the “Trustee”, which term includes any successor trustee under the Indenture), as to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee and the Holders and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the series designated on the face hereof, limited in aggregate principal amount to $50,000,000; provided, however, the aggregate principal amount hereof can be increased, without the consent of the Holder, as permitted by the provisions of the Original Indenture. The provisions of this Security, together with the provisions of the Indenture, shall govern the rights, obligations, duties and immunities of the Holder, the Company and the Trustee with respect to this Security, provided that, if any provision of this Security necessarily conflicts with any provision of the Indenture, the provision of this Security shall be controlling to the fullest extent permitted under the Indenture.

The Securities of this Series are subject to redemption upon not less than 30 nor more than 60 days’ notice by mail to the Holders of such Securities at their addresses in the Security Register for such Series at the option of the Company, in whole or in part, from time to time at a Redemption Price equal to the greater of (i) 100% of the principal amount of the Notes being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 20 basis points, plus, in each case, accrued interest thereon to the date of redemption.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes.

“Comparable Treasury Price” means, with respect to any redemption date, (1) the average of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) on the third Business Day preceding such redemption date, as set forth in the daily statistical release (or any successor release) published by the Federal Reserve Bank of New York and designated “Composite 3:30 p.m. Quotations for U.S. Government Securities” or (2) if such release (or any successor release) is not published or does not contain such prices on such third Business Day, the Reference Treasury Dealer Quotation for such redemption date.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer” means a primary U. S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

If notice has been given as provided in the Indenture and funds for redemption of any Securities (or any portion thereof) called for redemption shall have been made available on the Redemption Date referred to in such notice, such Securities (or any portion thereof) will cease to bear interest on the date fixed for such redemption specified in such notice and the only right of the Holders of such Securities will be to receive payment of the Redemption Price.

In the event of redemption of this Security in part only, a new Security or Securities of this Series and of like tenor for the unredeemed portion hereof will be issued in the name of the Holder hereof upon the cancellation hereof.

The Securities of this series will not be subject to any sinking fund.

If an Event of Default with respect to Securities of this series shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture.

Interest payments with respect to this Security will be computed and paid on the basis of a 360-day year of twelve 30-day months for the actual number of days elapsed.

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Securities of each series to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of a majority in principal amount of the Securities at the time Outstanding of all series to be affected (voting as a class). The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Securities of each Series at the time Outstanding, on behalf of the Holders of all Securities of such series, to waive compliance by the Company with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security.

No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of, premium, if any, and interest on this Security at the times, place and rate, and in the coin or currency, herein prescribed.

This Security shall be exchangeable for Securities registered in the names of Persons other than the Depositary with respect to such series or its nominee only as provided in the Indenture. This Security shall be so exchangeable if (x) the Depositary notifies the Company that it is unwilling or unable to continue as Depositary for such series or at any time ceases to be a clearing agency registered as such under the Exchange Act, (y) the Company executes and delivers to the Trustee an Officers’ Certificate providing that this Security shall be so exchangeable or (z) there shall have occurred and be continuing an Event of Default with respect to the Securities of such series. Securities so issued in exchange for this Security shall be of the same series, having the same interest rate, if any, and maturity and having the same terms as this Security, in authorized denominations and in the aggregate having the same principal amount as this Security and registered in such names as the Depositary for such Global Security shall direct.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of a Security of the series of which this Security is a part is registrable in the Security Register, upon surrender of this Security for registration of transfer at the office or agency of the Company in any place where the principal of and any premium and interest on this Security are payable, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the Security Registrar duly executed by, the Holder hereof or his attorney duly authorized in writing, and thereupon one or more new Securities of this Series and of like tenor, of authorized denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees.

The Securities of this Series are issuable only in registered form without coupons in denominations of $1,000 and any integral multiple thereof. As provided in the Indenture and subject to certain limitations therein set forth, Securities of this Series are exchangeable for a like aggregate principal amount of Securities of this Series and of like tenor of a different authorized denomination, as requested by the Holder surrendering the same.

No service charge shall be made for any such registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

Prior to due presentment of this Security for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name this Security is registered as the owner hereof for all purposes, whether or not this Security be overdue, and neither the Company, the Trustee nor any such agent shall be affected by notice to the contrary.

For so long as this Security is issued in the form of a Global Security, any notice to be given to the Holder of this Security shall be deemed to have been duly given to such Holder when given to the Depositary, or its nominee, in accordance with its Applicable Procedures. Neither the Company nor the Trustee will have any responsibility with respect to those policies and procedures or for any notices or other communications among the Depositary, its direct and indirect participants and the beneficial owners of this Security in global form.

If at any time this Security is not represented by a Global Security, any notice to be given to the Holder of this Security shall be deemed to have been duly given to such Holder upon the mailing of such notice to the Holder at such Holder’s address as it appears on the Security Register maintained by the Company or its agent as of the close of business preceding the day such notice is given.

Neither the failure to give any notice nor any defect in any notice given to the Holder of this Security or any other Security of this series will affect the sufficiency of any notice given to another Holder of any Securities of this series.

The Indenture provides that the Company, at its option, (a) will be discharged from any and all obligations in respect of the Securities (except for certain obligations to register the transfer or exchange of Securities, replace stolen, lost or mutilated Securities, maintain paying agencies and hold moneys for payment in trust) or (b) need not comply with certain restrictive covenants of the Indenture, in each case if the Company deposits, in trust, with the Trustee money or U.S. Government Obligations which, through the payment of interest thereon and principal thereof in accordance with their terms, will provide money, in an amount sufficient to pay all the principal of, and premium, if any, and interest, if any, on the Securities on the dates such payments are due in accordance with the terms of such Securities, and certain other conditions are satisfied.

No recourse shall be had for the payment of the principal of or the interest on this Security, or for any claim based hereon, or otherwise in respect hereof, or based on or in respect of the Indenture or any indenture supplemental thereto, against any incorporator, organizer, member, limited partner, stockholder, officer or director, as such, past, present or future, of the Company or any successor Person, whether by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability being, by the acceptance hereof and as part of the consideration for the issuance hereof, expressly waived and released.

This Security shall be governed by and construed in accordance with the laws of the State of New York without regard to principles of conflict of law except Section 5-1401 of the New York General Obligations Law.

All terms used in this Security which are defined in the Indenture shall have the meanings ascribed to them in the Indenture.

Unless the certificate of authentication hereon has been executed by the Trustee referred to herein by manual signature, this Security shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

IN WITNESS WHEREOF, Public Service Company of Oklahoma has caused this instrument to be duly executed under its corporate seal.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:
		Stephen P. Smith
		Treasurer

This is one of the Securities of the series designated herein and referred to in the within-mentioned Indenture.

Dated: June 7, 2004	THE BANK OF NEW YORK

	By:
		Authorized Signatory

FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s) unto

(PLEASE INSERT SOCIAL SECURITY OR OTHER

IDENTIFYING NUMBER OF ASSIGNEE)

_______________________________________

________________________________________________________________

(PLEASE PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF

________________________________________________________________

ASSIGNEE) the within Note and all rights thereunder, hereby

________________________________________________________________

irrevocably constituting and appointing such person attorney to

________________________________________________________________

transfer such Note on the books of the Issuer, with full

________________________________________________________________

power of substitution in the premises.

Dated:________________________ _________________________

NOTICE: The signature to this assignment must correspond with the name as written upon the face of the within Note in every particular, without alteration or enlargement or any change whatever and NOTICE: Signature(s) must be guaranteed by a financial institution that is a member of the Securities Transfer Agents Medallion Program (“STAMP”), the Stock Exchange Medallion Program (“SEMP”) or the New York Stock Exchange, Inc. Medallion Signature Program (“MSP”).

EXHIBIT 4(c)

PUBLIC SERVICE COMPANY OF OKLAHOMA

and

THE BANK OF NEW YORK,

AS TRUSTEE

___________________

FIFTH SUPPLEMENTAL INDENTURE

Dated as of May 20, 2005

Supplemental to the Indenture

dated as of November 1, 2000

4.70% Senior Notes, Series E, due 2011

FIFTH SUPPLEMENTAL INDENTURE, dated as of May 20, 2005, between PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the “Company”), and THE BANK OF NEW YORK, a New York banking corporation organized and existing under the laws of the State of New York, as Trustee under the Original Indenture referred to below (the “Trustee”).

RECITALS OF THE COMPANY

The Company desires to create a series of the Senior Notes in an aggregate principal amount of $75,000,000 to be designated the “4.70% Senior Notes, Series E, due 2011” (the “4.70% Senior Notes”), and all action on the part of the Company necessary to authorize the issuance of the 4.70% Senior Notes under the Original Indenture and this Fifth Supplemental Indenture has been duly taken.

All acts and things necessary to make the 4.70% Senior Notes, when executed by the Company and completed, authenticated and delivered by the Trustee as provided in the Original Indenture and this Fifth Supplemental Indenture, the valid and binding obligations of the Company and to constitute these presents a valid and binding supplemental indenture and agreement according to its terms, have been done and performed.

NOW, THEREFORE, THIS FIFTH SUPPLEMENTAL INDENTURE WITNESSETH:

ARTICLE ONE

Definitions

ARTICLE TWO

Terms and Issuance of the 4.70% Senior Notes

SECTION 201. Issue of 4.70% Senior Notes

A series of Senior Notes which shall be designated the “4.70% Senior Notes, Series E, due 2011” shall be executed, authenticated and delivered from time to time in accordance with the provisions of, and shall in all respects be subject to, the terms, conditions and covenants of, the Original Indenture and this Fifth Supplemental Indenture (including the form of Global Security set forth in Exhibit A hereto). The aggregate principal amount of the 4.70% Senior Notes, which may be authenticated and delivered under this Fifth Supplemental Indenture shall initially be $75,000,000, and such principal amount of the 4.70% Senior Notes may be increased from time to time. All 4.70% Senior Notes need not be issued at the same time and such series may be reopened at any time, without the consent of any Holder, for issuance of additional 4.70% Senior Notes. Any such additional 4.70% Senior Notes will have the same interest rate, maturity and other terms as those initially issued.

SECTION 202. Form of 4.70% Senior Notes, Incorporation of Terms

SECTION 203. Depositary for Global Securities

The Depositary for any Global Securities of the series of which this 4.70% Senior Note is a part shall be The Depository Trust Company in The City of New York.

SECTION 204. Restrictions on Liens

The covenant contained in Section 1007 of the Original Indenture shall not be applicable to the 4.70% Senior Notes.

So long as any of the 4.70% Senior Notes are outstanding, the Company will not create or suffer to be created or to exist any additional mortgage, pledge, security interest, or other lien (collectively “Liens”) on any of its utility properties or tangible assets now owned or hereafter acquired to secure any indebtedness for borrowed money (“Secured Debt”), without providing that the 4.70% Senior Notes will be similarly secured. This restriction does not apply to the Company’s subsidiaries, nor will it prevent any of them from creating or permitting to exist Liens on their property or assets to secure any Secured Debt. Further, this restriction on Secured Debt does not apply to the Company’s existing first mortgage bonds that have previously been issued under its Mortgage and Deed of Trust, dated July 1, 1945, between the Company and Liberty Bank and Trust Company of Tulsa, National Association, as successor to The First National Bank and Trust Company of Tulsa, now The Bank of New York, as successor Trustee or any indenture supplemental thereto; provided that this restriction will apply to future issuances thereunder (other than issuances of refunding first mortgage bonds). In addition, this restriction does not prevent the creation or existence of:

	(a)	Liens on property existing at the time of acquisition or construction of such property (or created within one year after completion of such acquisition or construction), whether by purchase, merger, construction or otherwise, or to secure the payment of all or any part of the purchase price or construction cost thereof, including the extension of any Liens to repairs, renewals, replacements, substitutions, betterments, additions, extensions and improvements then or thereafter made on the property subject thereto;

	(b)	Financing of the Company’s accounts receivable for electric service;

	(c)	Any extensions, renewals or replacements (or successive extensions, renewals or replacements), in whole or in part, of liens permitted by the foregoing clauses; and

	(d)	The pledge of any bonds or other securities at any time issued under any of the Secured Debt permitted by the above clauses.

In addition to the permitted issuances above, Secured Debt not otherwise so permitted may be issued in an amount that does not exceed 15% of Net Tangible Assets as defined below.

This restriction also does not apply to or prevent the creation or existence of leases made, or existing on property acquired, in the ordinary course of business.

SECTION 205. Place of Payment

SECTION 206. Sinking Funds .

Article Twelve of the Indenture shall not apply to the 4.70% Senior Notes.

SECTION 207. Redemption

The 4.70% Senior Notes shall be redeemable at the option of the Company, in whole at any time or in part from time to time, upon not less than thirty but not more than sixty days’ previous notice given by mail to the registered owners of the 4.70% Senior Notes at a redemption price equal to the greater of (i) 100% of the principal amount of the 4.70% Senior Notes being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the 4.70% Senior Notes being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 15 basis points, plus, in each case, accrued interest thereon to the date of redemption.

“Comparable Treasury Price” means, with respect to any redemption date, (1) the average of the Reference Treasury Dealer Quotations for such redemption date after excluding the highest and lowest such Reference Treasury Dealer Quotations, or (2) if fewer than four such Reference Treasury Dealer Quotations are obtained, the average of all such quotations.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer” means a primary U.S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer Quotation” means, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the third Business Day preceding such redemption date.

ARTICLE THREE

Miscellaneous

SECTION 301. Execution as Supplemental Indenture

This Fifth Supplemental Indenture is executed and shall be construed as an indenture supplemental to the Original Indenture and, as provided in the Original Indenture, this Fifth Supplemental Indenture forms a part thereof.

SECTION 302. Conflict with Trust Indenture Act

If any provision hereof limits, qualifies or conflicts with another provision hereof which is required to be included in this Fifth Supplemental Indenture by any of the provisions of the Trust Indenture Act, such required provision shall control.

SECTION 303. Effect of Headings

The Article and Section headings herein are for convenience only and shall not affect the construction hereof.

SECTION 304. Successors and Assigns

All covenants and agreements by the Company in this Fifth Supplemental Indenture shall bind its successors and assigns, whether so expressed or not.

SECTION 305. Separability Clause

In case any provision in this Fifth Supplemental Indenture or in the 4.70% Senior Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 306. Benefits of Fifth Supplemental Indenture

Nothing in this Fifth Supplemental Indenture or in the 4.70% Senior Notes, express or implied, shall give to any Person, other than the parties hereto and their successors hereunder and the Holders, any benefit or any legal or equitable right, remedy or claim under this Fifth Supplemental Indenture.

SECTION 307. Execution and Counterparts

This Fifth Supplemental Indenture may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, the parties hereto have caused this Fifth Supplemental Indenture to be duly executed and attested, all as of the day and year first above written.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:	/s/ Stephan T. Haynes
		Assistant Treasurer
Attest:
/s/ Thomas G. Berkemeyer
Assistant Secretary
		THE BANK OF NEW YORK,
		as Trustee

	By:	/s/ Van K. Brown
		Authorized Signatory
Attest:
/s/ Remo J. Reale
Name: Remo J. Reale
Title: Vice President

STATE OF OHIO	)
	)	: ss
COUNTY OF FRANKLIN	)

On the 5th day of May, 2005, personally appeared before me, a Notary Public within and for said County in the State of Ohio, Stephan T. Haynes and Thomas G. Berkemeyer, to me known and known to me to be respectively an Assistant Treasurer and an Assistant Secretary of Public Service Company of Oklahoma, one of the corporations named in and which executed the foregoing instrument, who severally acknowledged that they did sign said instrument as such Assistant Treasurer and Assistant Secretary for and on behalf of said corporation and that the same is their free act and deed as such Assistant Treasurer and Assistant Secretary, respectively, and the free and corporate act and deed of said corporation.

In witness whereof, I have hereunto set my hand notarial seal this 19th day of May, 2005.

	/s/ Ann B. Graf
	Notary Public, State of Ohio Attorney at Law No Expiration Date

STATE OF NEW YORK	)
	)	: ss
COUNTY OF NEW YORK	)

On the 20th day of May, 2005, personally appeared before me, a Notary Public within and for said County in the State of New York, Van K. Brown and Remo J. Reale, to me known and known to me to be respectively the Vice President and Vice President of The Bank of New York, one of the corporations named in and which executed the foregoing instrument, who severally acknowledged that they did sign said instrument as such Vice President and Vice President for and on behalf of said corporation and that the same is their free act and deed as such Vice President and Vice President, respectively, and the free and corporate act and deed of said corporation.

In witness whereof, I have hereunto set my hand notarial seal this 20th day of May, 2005.

	/s/ William J. Casssels
	Notary Public, State of New York Expires May 18, 2006

EXHIBIT A TO EXHIBIT 4( c )

No. R-1

PUBLIC SERVICE COMPANY OF OKLAHOMA

4.70% Senior Notes, Series E, due 2011

CUSIP No. 744533 BG 4

$75,000,000

PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the “Company”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to CEDE & CO. or registered assigns, the principal sum of SEVENTY-FIVE MILLION DOLLARS ($75,000,000) on May 15, 2011 (the “Final Maturity”), and to pay interest thereon from May 20, 2005 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on May 15 and November 15 each year, commencing November 15, 2005, at the interest rate per annum specified above, until the principal amount shall have been paid or duly provided for. Interest shall be computed on the basis of a 360-day year of twelve 30-day months.

The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the April 30 or October 31 (whether or not a Business Day) immediately preceding the Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture.

This Security is one of a duly authorized issue of securities of the Company (the “Securities”), issued and to be issued in one or more series under an Indenture, dated as of November 1, 2000, as amended and supplemented from time to time (the “Indenture”, which term shall have the meaning assigned to it in such instrument), between the Company and The Bank of New York, a New York banking corporation, as Trustee (the “Trustee”, which term includes any successor trustee under the Indenture), as to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee and the Holders and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the series designated on the face hereof, limited in aggregate principal amount to $75,000,000; provided, however, the aggregate principal amount hereof can be increased, without the consent of the Holder, as permitted by the provisions of the Original Indenture. The provisions of this Security, together with the provisions of the Indenture, shall govern the rights, obligations, duties and immunities of the Holder, the Company and the Trustee with respect to this Security, provided that, if any provision of this Security necessarily conflicts with any provision of the Indenture, the provision of this Security shall be controlling to the fullest extent permitted under the Indenture.

The Securities of this Series are subject to redemption upon not less than 30 nor more than 60 days’ notice by mail to the Holders of such Securities at their addresses in the Security Register for such Series at the option of the Company, in whole or in part, from time to time at a Redemption Price equal to the greater of (i) 100% of the principal amount of the Securities being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the Securities being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 15 basis points, plus, in each case, accrued interest thereon to the date of redemption.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the Securities that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Securities.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer” means a primary U. S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

“Reference Treasury Dealer Quotations” mean, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the third Business Day preceding such redemption date.

The Securities of this series will not be subject to any sinking fund.

Interest payments with respect to this Security will be computed and paid on the basis of a 360-day year of twelve 30-day months for the actual number of days elapsed.

All terms used in this Security which are defined in the Indenture shall have the meanings ascribed to them in the Indenture.

IN WITNESS WHEREOF, Public Service Company of Oklahoma has caused this instrument to be duly executed.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:
		Assistant Treasurer

This is one of the Securities of the series designated herein and referred to in the within-mentioned Indenture.

Date: May 20, 2005		THE BANK OF NEW YORK,

	By:
		Authorized Signatory

FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s) unto

(PLEASE INSERT SOCIAL SECURITY OR OTHER

IDENTIFYING NUMBER OF ASSIGNEE)

_______________________________________

________________________________________________________________

(PLEASE PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF

________________________________________________________________

ASSIGNEE) the within Note and all rights thereunder, hereby

________________________________________________________________

irrevocably constituting and appointing such person attorney to

________________________________________________________________

transfer such Note on the books of the Issuer, with full

________________________________________________________________

power of substitution in the premises.

Dated:________________________ _________________________

EXHIBIT 4(d)

PUBLIC SERVICE COMPANY OF OKLAHOMA

and

THE BANK OF NEW YORK,

AS TRUSTEE

___________________

________ SUPPLEMENTAL INDENTURE

Dated as of ____________, ____

Supplemental to the Indenture

dated as of November 1, 2000

____% Senior Notes, Series _, due ____

________ SUPPLEMENTAL INDENTURE, dated as of ____________, ____, between PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the "Company"), and THE BANK OF NEW YORK, a New York banking corporation organized and existing under the laws of the State of New York, as Trustee under the Original Indenture referred to below (the "Trustee").

RECITALS OF THE COMPANY

The Company has heretofore executed and delivered to the Trustee an indenture dated as of November 1, 2000 (the "Original Indenture"), to provide for the issuance from time to time of its debentures, notes or other evidences of indebtedness (the "Senior Notes"), the form and terms of which are to be established as set forth in Section 201 and 301 of the Original Indenture.

The Company desires to create a series of the Senior Notes in an aggregate principal amount of $____________ to be designated the "____% Senior Notes, Series _, due ____" (the "____% Senior Notes"), and all action on the part of the Company necessary to authorize the issuance of the ____% Senior Notes under the Original Indenture and this ________ Supplemental Indenture has been duly taken.

All acts and things necessary to make the ____% Senior Notes, when executed by the Company and completed, authenticated and delivered by the Trustee as provided in the Original Indenture and this ________ Supplemental Indenture, the valid and binding obligations of the Company and to constitute these presents a valid and binding supplemental indenture and agreement according to its terms, have been done and performed.

NOW, THEREFORE, THIS ________ SUPPLEMENTAL INDENTURE WITNESSETH:

That in consideration of the premises and of the acceptance and purchase of the ____% Senior Notes by the Holders thereof and of the acceptance of this trust by the Trustee, the Company covenants and agrees with the Trustee, for the equal benefit of the Holders of the ____% Senior Notes, as follows:

ARTICLE ONE

Definitions

ARTICLE TWO

Terms and Issuance of the ____% Senior Notes

SECTION 201. Issue of ____% Senior Notes

A series of Senior Notes which shall be designated the "____% Senior Notes, Series _, due ____" shall be executed, authenticated and delivered from time to time in accordance with the provisions of, and shall in all respects be subject to, the terms, conditions and covenants of, the Original Indenture and this ________ Supplemental Indenture (including the form of Global Security set forth in Exhibit A hereto). The aggregate principal amount of the ____% Senior Notes, which may be authenticated and delivered under this ________ Supplemental Indenture shall not, except as permitted by the provisions of the Original Indenture, exceed $_____________.

SECTION 202. Form of ____% Senior Notes, Incorporation of Terms

The ____% Senior Notes shall be substantially in the form of the Global Security attached hereto as Exhibit A . The terms of such ____% Senior Notes are herein incorporated by reference and are part of this ________ Supplemental Indenture.

SECTION 203. Depositary for Global Securities

The Depositary for any Global Securities of the series of which this ____% Senior Note is a part shall be The Depository Trust Company in The City of New York.

SECTION 204. Restrictions on Liens

The covenant contained in Section 1007 of the Original Indenture shall not be applicable to the ____% Senior Notes.

So long as any of the ____% Senior Notes are outstanding, the Company will not create or suffer to be created or to exist any additional mortgage, pledge, security interest, or other lien (collectively "Liens") on any of its utility properties or tangible assets now owned or hereafter acquired to secure any indebtedness for borrowed money ("Secured Debt"), without providing that the ____% Senior Notes will be similarly secured. This restriction does not apply to the Company's subsidiaries, nor will it prevent any of them from creating or permitting to exist Liens on their property or assets to secure any Secured Debt. Further, this restriction on Secured Debt does not apply to the Company's existing first mortgage bonds that have previously been issued under its Mortgage and Deed of Trust, dated July 1, 1945, between the Company and Liberty Bank and Trust Company of Tulsa, National Association, as successor to The first National Bank and Trust Company of Tulsa, as Trustee or any indenture supplemental thereto; provided that this restriction will apply to future issuances thereunder (other than issuances of refunding first mortgage bonds). In addition, this restriction does not prevent the creation or existence of:

(b) Financing of the Company's accounts receivable for electric service;

(c) Any extensions, renewals or replacements (or successive extensions, renewals or replacements), in whole or in part, of liens permitted by the foregoing clauses; and

(d) The pledge of any bonds or other securities at any time issued under any of the Secured Debt permitted by the above clauses.

In addition to the permitted issuances above, Secured Debt not otherwise so permitted may be issued in an amount that does not exceed 15% of Net Tangible Assets as defined below.

"Net Tangible Assets" means the total of all assets (including revaluations thereof as a result of commercial appraisals, price level restatement or otherwise) appearing on the Company's balance sheet, net of applicable reserves and deductions, but excluding goodwill, trade names, trademarks, patents, unamortized debt discount and all other like intangible assets (which term shall not be construed to include such revaluations), less the aggregate of the Company's current liabilities appearing on such balance sheet. For purposes of this definition, the Company's balance sheet does not include assets and liabilities of its subsidiaries.

This restriction also does not apply to or prevent the creation or existence of leases made, or existing on property acquired, in the ordinary course of business.

SECTION 205. Place of Payment

The Place of Payment in respect of the ____% Senior Notes will be at the principal office or place of business of the Trustee or its successor in trust under the Indenture, which, at the date hereof, is located at 101 Barclay Street, New York, NY 10281, Attention: Corporate Trust Trustee.

SECTION 206. Sinking Funds .

Article Twelve of the Indenture shall not apply to the Series _ Notes.

SECTION 207. Redemption

The ____% Senior Notes shall be redeemable at the option of the Company, in whole at any time or in part from time to time, upon not less than thirty but not more than sixty days' previous notice given by mail to the registered owners of the ____% Senior Notes at a redemption price equal to the greater of (i) 100% of the principal amount of the ____% Senior Notes being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the ____% Senior Notes being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 20 basis points, plus, in each case, accrued interest thereon to the date of redemption.

"Comparable Treasury Issue" means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the ____% Senior Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes.

"Comparable Treasury Price" means, with respect to any redemption date, (i) the average of the bid and asked prices for the Comparable Treasury Issue (expressed in each case a percentage of its principal amount) on the third Business Day preceding such redemption date, as set forth in the daily statistical release (or any successor release) published by the Federal Reserve Bank of New York and designated "Composite 3:30 p.m. Quotations for U. S. Government Securities" or (ii) if such release (or any successor release) is not published or does not contain such prices on such third Business Day, the Reference Treasury Dealer Quotation for such redemption date.

"Independent Investment Banker" means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

"Reference Treasury Dealer" means a primary U.S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

"Reference Treasury Dealer Quotation" means, with respect to the Reference Treasury Dealer and any redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at or before 5:00 p.m., New York City time, on the third Business Day preceding such redemption date.

"Treasury Rate" means, with respect to any redemption date, the rate per annum equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date.

ARTICLE THREE

Miscellaneous

SECTION 301. Execution as Supplemental Indenture

This ________ Supplemental Indenture is executed and shall be construed as an indenture supplemental to the Original Indenture and, as provided in the Original Indenture, this ________ Supplemental Indenture forms a part thereof.

SECTION 302. Conflict with Trust Indenture Act

If any provision hereof limits, qualifies or conflicts with another provision hereof which is required to be included in this ________ Supplemental Indenture by any of the provisions of the Trust Indenture Act, such required provision shall control.

SECTION 303. Effect of Headings

The Article and Section headings herein are for convenience only and shall not affect the construction hereof.

SECTION 304. Successors and Assigns

All covenants and agreements by the Company in this ________ Supplemental Indenture shall bind its successors and assigns, whether so expressed or not.

SECTION 305. Separability Clause

In case any provision in this ________ Supplemental Indenture or in the ____% Senior Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 306. Benefits of ________ Supplemental Indenture

Nothing in this ________ Supplemental Indenture or in the ____% Senior Notes, express or implied, shall give to any Person, other than the parties hereto and their successors hereunder and the Holders, any benefit or any legal or equitable right, remedy or claim under this ________ Supplemental Indenture.

SECTION 307. Execution and Counterparts

This ________ Supplemental Indenture may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, the parties hereto have caused this ________ Supplemental Indenture to be duly executed and their respective corporate seals to be hereunto affixed and attested, all as of the day and year first above written.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:	/s/
		Assistant Treasurer
Attest:
/s/
Assistant Secretary

		THE BANK OF NEW YORK,
		as Trustee

	By:	/s/
		Authorized Signatory
Attest:
/s/
Name:
Title:

STATE OF OHIO	)
	)	ss:
COUNTY OF FRANKLIN	)

On the ____ day of __________, ____, before me personally came _______________, to me known, who, being by me duly sworn, did depose and say that ___ is an Assistant Treasurer of Public Service Company of Oklahoma, one of the corporations described in and which executed the foregoing instrument; that ____knows the seal of said corporation; that the seal affixed to said instrument is such corporate seal; that it was so affixed by authority of the Board of Directors of said corporation, and that ___ signed ___ name thereto by like authority.


	My Commission expires

STATE OF NEW YORK	)
	)	ss:
COUNTY OF NEW YORK	)

On the ____ day of __________, ____, before me personally came _______________, to me known, who, being by me duly sworn, did depose and say that ___ is an Assistant Treasurer of The Bank of New York, a New York banking corporation, one of the corporations described in and which executed the foregoing instrument; that ___ knows the seal of said corporation; that the seal affixed to said instrument is such corporate seal; that it was so affixed by authority of the Board of Directors of said corporation, and that ___ signed ___ name thereto by like authority.


	My Commission expires

EXHIBIT A to EXHIBIT 4(d)

[Form of Face of Global Security]

Unless this certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation ("DTC"), to Public Service Company of Oklahoma or its agent for registration of transfer, exchange or payment, and any definitive certificate issued is registered in the name of Cede & Co. or in such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL in as much as the registered owner hereof, Cede & Co., has an interest herein.

No. R-1

PUBLIC SERVICE COMPANY OF OKLAHOMA

____% Senior Notes, Series _, due ____

CUSIP No. __________

$____________

PUBLIC SERVICE COMPANY OF OKLAHOMA, a corporation duly organized and existing under the laws of the State of Oklahoma (the "Company", which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to CEDE & CO. or registered assigns, the principal sum of _________________________ DOLLARS ($____________) on ____________, ____ (the "Final Maturity"), and to pay interest thereon from ____________, ____ or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on March 15 and ____________ each year, commencing March 15, ____, at the interest rate per annum specified above, until the principal amount shall have been paid or duly provided for. Interest shall be computed on the basis of a 360-day year of twelve 30-day months.

The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the February 28 or August 31 (whether or not a Business Day) immediately preceding the Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture.

This Security has initially been issued in the form of a Global Security, and the Company has initially designated The Depository Trust Company (the "Depositary", which term shall include any successor depositary) as the depositary for this Security. For as long as this Security or any portion hereof is issued in such form, and notwithstanding the previous paragraph, all payments of interest, principal and other amounts in respect of this Security or portion thereof shall be made to the Depositary or its nominee in accordance with the Applicable Procedures in the coin or currency specified above and as further provided herein.

This Security is one of a duly authorized issue of securities of the Company (the "Securities"), issued and to be issued in one or more series under an Indenture, dated as of November 1, 2000, as amended and supplemented from time to time (the "Indenture", which term shall have the meaning assigned to it in such instrument), between the Company and The Bank of New York, a New York banking corporation, as Trustee (the "Trustee", which term includes any successor trustee under the Indenture), as to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee and the Holders and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the series designated on the face hereof, limited in aggregate principal amount to $____________; provided, however, the aggregate principal amount hereof can be increased, without the consent of the Holder, as permitted by the provisions of the Original Indenture. The provisions of this Security, together with the provisions of the Indenture, shall govern the rights, obligations, duties and immunities of the Holder, the Company and the Trustee with respect to this Security, provided that, if any provision of this Security necessarily conflicts with any provision of the Indenture, the provision of this Security shall be controlling to the fullest extent permitted under the Indenture.

The Securities of this Series are subject to redemption upon not less than 30 nor more than 60 days' notice by mail to the Holders of such Securities at their addresses in the Security Register for such Series at the option of the Company, in whole or in part, from time to time at a Redemption Price equal to the greater of (i) 100% of the principal amount of the Notes being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes being redeemed (excluding the portion of any such interest accrued to the date of redemption) discounted (for purposes of determining present value) to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 20 basis points, plus, in each case, accrued interest thereon to the date of redemption.

"Comparable Treasury Issue" means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes.

"Comparable Treasury Price" means, with respect to any redemption date, (1) the average of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) on the third Business Day preceding such redemption date, as set forth in the daily statistical release (or any successor release) published by the Federal Reserve Bank of New York and designated "Composite 3:30 p.m. Quotations for U.S. Government Securities" or (2) if such release (or any successor release) is not published or does not contain such prices on such third Business Day, the Reference Treasury Dealer Quotation for such redemption date.

"Independent Investment Banker" means one of the Reference Treasury Dealers appointed by the Company and reasonably acceptable to the Trustee.

"Reference Treasury Dealer" means a primary U. S. government securities dealer in New York City selected by the Company and reasonably acceptable to the Trustee.

The Securities of this series will not be subject to any sinking fund.

Interest payments with respect to this Security will be computed and paid on the basis of a 360-day year of twelve 30-day months for the actual number of days elapsed.

This Security shall be exchangeable for Securities registered in the names of Persons other than the Depositary with respect to such series or its nominee only as provided in the Indenture. This Security shall be so exchangeable if (x) the Depositary notifies the Company that it is unwilling or unable to continue as Depositary for such series or at any time ceases to be a clearing agency registered as such under the Exchange Act, (y) the Company executes and delivers to the Trustee an Officers' Certificate providing that this Security shall be so exchangeable or (z) there shall have occurred and be continuing an Event of Default with respect to the Securities of such series. Securities so issued in exchange for this Security shall be of the same series, having the same interest rate, if any, and maturity and having the same terms as this Security, in authorized denominations and in the aggregate having the same principal amount as this Security and registered in such names as the Depositary for such Global Security shall direct.

If at any time this Security is not represented by a Global Security, any notice to be given to the Holder of this Security shall be deemed to have been duly given to such Holder upon the mailing of such notice to the Holder at such Holder's address as it appears on the Security Register maintained by the Company or its agent as of the close of business preceding the day such notice is given.

All terms used in this Security which are defined in the Indenture shall have the meanings ascribed to them in the Indenture.

IN WITNESS WHEREOF, Public Service Company of Oklahoma has caused this instrument to be duly executed under its corporate seal.

	PUBLIC SERVICE COMPANY OF OKLAHOMA

	By:
		Assistant Treasurer

This is one of the Securities of the series designated herein and referred to in the within-mentioned Indenture.

Dated: _______________	THE BANK OF NEW YORK

	By:
		Authorized Signatory

FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s) unto

(PLEASE INSERT SOCIAL SECURITY OR OTHER

IDENTIFYING NUMBER OF ASSIGNEE)

_______________________________________

________________________________________________________________

(PLEASE PRINT OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF

________________________________________________________________

ASSIGNEE) the within Note and all rights thereunder, hereby

________________________________________________________________

irrevocably constituting and appointing such person attorney to

________________________________________________________________

transfer such Note on the books of the Issuer, with full

________________________________________________________________

power of substitution in the premises.

Dated:________________________ _________________________

NOTICE: The signature to this assignment must correspond with the name as written upon the face of the within Note in every particular, without alteration or enlargement or any change whatever and NOTICE: Signature(s) must be guaranteed by a financial institution that is a member of the Securities Transfer Agents Medallion Program ("STAMP"), the Stock Exchange Medallion Program ("SEMP") or the New York Stock Exchange, Inc. Medallion Signature Program ("MSP").

EXHIBIT 5

Public Service Company of Oklahoma

1 Riverside Plaza

Columbus, Ohio 43215

April 26, 2006

Ladies and Gentlemen:

I am an employee of American Electric Power Service Corporation, a New York corporation and a service company affiliate of Public Service Company of Oklahoma, an Oklahoma corporation (the “Company”). I have acted as counsel to the Company in connection with the Registration Statement on Form S-3 (the “Registration Statement”) filed by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), relating to Unsecured Notes (the “Unsecured Notes”) to be issued under an Indenture, dated as of November 1, 2000 (the “Indenture”), between the Company and The Bank of New York, as Trustee (the “Trustee”). The Unsecured Notes may be issued and sold or delivered from time to time as set forth in the Registration Statement, any amendment thereto, the prospectus contained therein (the “Prospectus”) and supplements to the Prospectus and pursuant to Rule 415 under the Act for an aggregate initial offering price not to exceed $450,000,000.

I have examined the Registration Statement and the Indenture, which has been filed with the Commission as an exhibit to the Registration Statement. I also have examined the originals, or duplicates or certified or conformed copies, of such corporate records, agreements, documents and other instruments and have made such other investigations as I have deemed relevant and necessary in connection with the opinions hereinafter set forth. As to questions of fact material to this opinion, I have relied upon certificates or comparable documents of public officials and of officers and representatives of the Company.

In rendering the opinions set forth below, I have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to me as originals, the conformity to original documents of all documents submitted to me as duplicates or certified or conformed copies and the authenticity of the originals of such latter documents. I also have assumed that: (1) the Indenture is the valid and legally binding obligation of the Trustee; and (2) the Company is validly existing under the laws of Oklahoma.

I have assumed further that (1) the Company has duly authorized, executed and delivered the Indenture and (2) execution, delivery and performance by the Company of the Indenture and the Unsecured Notes do not and will not violate the laws of Oklahoma or any other applicable laws (excepting the laws of the State of New York and the Federal laws of the United States).

Based upon the foregoing, and subject to the qualifications and limitations stated herein, I am of the opinion that: assuming (a) the taking of all necessary corporate action to approve the issuance and terms of the Unsecured Notes, the terms of the offering thereof and related matters by the Board of Directors of the Company, a duly constituted and acting committee of such Board or duly authorized officers of the Company (such Board of Directors, committee or authorized officers being referred to herein as the “Board”) and (b) the due execution, authentication, issuance and delivery of such Unsecured Notes, upon payment of the consideration therefore provided for in the applicable definitive purchase, underwriting or similar agreement approved by the Board and otherwise in accordance with the provisions of the Indenture and such agreement, such Unsecured Notes will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms, subject to the effects of (i) bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally; (ii) general equitable principles (whether considered in a proceeding in equity or at law); and (iii) an implied covenant of good faith and fair dealing.

I do not express any opinion herein concerning any law other than the law of the State of New York and the Federal law of the United States.

I hereby consent to the filing of this opinion letter as Exhibit 5 to the Registration Statement and to the use of my name under the caption “Legal Opinions” in the Prospectus included in the Registration Statement.

Very truly yours,

/s/ Thomas G. Berkemeyer

Thomas G. Berkemeyer

EXHIBIT 23.(a)

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Registration Statement on Form S-3 of our reports dated February 27, 2006 relating to the financial statements (and with respect to the report on those financial statements, expressed an unqualified opinion and included an explanatory paragraph concerning the adoption of new accounting pronouncements in 2003 and 2004) and financial statement schedule of Public Service Company of Oklahoma appearing in and incorporated by reference in the Annual Report on Form 10-K of Public Service Company of Oklahoma for the year ended December 31, 2005 and to the reference to us under the heading “Experts” in the Prospectus, which is part of this Registration Statement.

/s/ Deloitte & Touche LLP

Columbus, Ohio

April 26, 2006

EXHIBIT 24

PUBLIC SERVICE COMPANY OF OKLAHOMA

POWER OF ATTORNEY

Each of the undersigned directors or officers of PUBLIC SERVICE COMPANY OF OKLAHOMA, an Oklahoma corporation, which is to file with the Securities and Exchange Commission, Washington, D.C. 20549, under the provisions of the Securities Act of 1933, as amended, one or more Registration Statements for the registration thereunder of up to $375,000,000 aggregate principal amount of its Debt Securities, including up to $375,000,000 of new indebtedness, comprised of unsecured promissory notes in one or more new series, each series to have a maturity not exceeding 60 years, does hereby appoint MICHAEL G. MORRIS, SUSAN TOMASKY, STEPHEN P. SMITH and STEPHAN T. HAYNES his or her true and lawful attorneys, and each of them his or her true and lawful attorney, with power to act without the others, and with full power of substitution or resubstitution, to execute for him or her and in his or her name said Registration Statement(s) and any and all amendments thereto, whether said amendments add to, delete from or otherwise alter the Registration Statement(s) or the related Prospectus(es) included therein, or add or withdraw any exhibits or schedules to be filed therewith and any and all instruments necessary or incidental in connection therewith, hereby granting unto said attorneys and each of them full power and authority to do and perform in the name and on behalf of each of the undersigned, and in any and all capacities, every act and thing whatsoever required or necessary to be done in and about the premises, as fully and to all intents and purposes as each of the undersigned might or could do in person, hereby ratifying and approving the acts of said attorneys and each of them.

IN WITNESS WHEREOF the undersigned have hereunto set their hands this 28 ^th day of February, 2006.

/s/ Michael G. Morris	/s/ Robert P. Powers
Michael G. Morris L.S.	Robert P. Powers L.S.

/s/ Carl L. English	/s/ Stephen P. Smith
Carl L. English L.S	Stephen P. Smith L.S.

/s/ Thomas M. Hagan	/s/ Susan Tomasky
Thomas M. Hagan L.S.	Susan Tomasky L.S.

/s/ John B. Keane	/s/ Dennis E. Welch
John B. Keane L.S.	Dennis E. Welch L.S.

/s/ Venita McCellon-Allen
Venita McCellon-Allen L.S.

PUBLIC SERVICE COMPANY OF OKLAHOMA

I, Thomas G. Berkemeyer, Assistant Secretary of PUBLIC SERVICE COMPANY OF OKLAHOMA, HEREBY CERTIFY that the following constitutes a true and exact copy of the resolutions duly adopted by the affirmative vote of a majority of the Board of Directors of said Company at a meeting of said Board duly and legally held on February 28, 2006, at which meeting a quorum of the Board of Directors of said Company was present and voting throughout. I further certify that said resolutions have not been altered, amended or rescinded, and that they are presently in full force and effect.

GIVEN under my hand this 21st day of April, 2006.

/s/ Thomas G. Berkemeyer

Assistant Secretary

PUBLIC SERVICE COMPANY OF OKLAHOMA

February 28, 2006

The Chairman outlined a proposed financing program through December 31, 2007 of the Company involving the issuance and sale, either at competitive bidding, through a negotiated public offering with one or more agents or underwriters or through private placement, of up to $375,000,000 (or its equivalent in another currency or composite currency) aggregate principal amount of debt securities comprised of unsecured promissory notes, in one or more new series, each series to have a maturity of not more than 60 years ("Debt Securities"). He then stated that, as an alternative to issuing Debt Securities, the Company may issue one or more unsecured promissory notes ("AEP Notes") to American Electric Power Company, Inc. ("AEP") in an aggregate principal amount of up to $375,000,000. The Debt Securities and the AEP Notes would be issued in compliance with the order of the Oklahoma Corporation Commission dated November 28, 2005.

The Chairman explained that it was proposed that the proceeds to be received in connection with the proposed sale of Debt Securities or the AEP Notes would be added to the general funds of the Company and used to redeem directly or indirectly long-term debt, to refund directly or indirectly preferred stock, to repay short-term debt at or prior to maturity, to reimburse the Company's treasury for expenditures incurred in connection with its construction program, to replenish working capital and for other corporate purposes.

Thereupon, on motion duly made and seconded, it was unanimously

RESOLVED, that the proposed financing program of this Company, as outlined at this meeting, be, and the same hereby is, in all respects ratified, confirmed and approved; and further

RESOLVED, that the proper persons be, and they hereby are, authorized to take all steps necessary, or in their opinion desirable, to carry out the financing program outlined at this meeting.

The Chairman stated that the Company on November 28, 2005 had received an Order from the Oklahoma State Corporation Commission authorizing the issuance of $375,000,000 of Debt Securities and/or AEP Notes. He then stated that it may be necessary to file one or more Registration Statements pursuant to the applicable provisions of the Securities Act of 1933, as amended, and to register or qualify the securities to be sold pursuant to such financing program under the "blue sky" laws of various jurisdictions.

Thereupon, on motion duly made and seconded, it was unanimously

RESOLVED, that with respect to the proposed financing program approved at this meeting, the actions of the proper officers of this Company in connection with the execution and filing on behalf of the Company of the necessary application with the Oklahoma Corporation Commission be, and they hereby are, ratified, confirmed and approved in all respects; and further

RESOLVED, that the proper persons be, and they hereby are, authorized to execute and file with the Securities and Exchange Commission ("SEC") on behalf of the Company one or more Registration Statements pursuant to the applicable provisions of the Securities Act of 1933, as amended; and further

RESOLVED, that it is desirable and in the best interest of the Company that the Debt Securities be qualified or registered for sale in various jurisdictions; that (i) the Chairman of the Board, the President, the Treasurer or any Assistant Treasurer of the Company or (ii) any Executive Vice President of American Electric Power Service Corporation (“Authorized Persons”), be, and they hereby are, authorized to determine the jurisdictions in which appropriate action shall be taken to qualify or register for sale all or such part of the Debt Securities of the Company as said Authorized Persons may deem advisable; that said Authorized Persons are hereby authorized to perform on behalf of the Company any and all such acts as they may deem necessary or advisable in order to comply with the applicable laws of any such jurisdictions, and in connection therewith to execute and file all requisite papers and documents, including, but not limited to, applications, reports, surety bonds, irrevocable consents and appointments of attorneys for service of process; and the execution by such Authorized Persons of any such paper or document or the doing by them of any act in connection with the foregoing matters shall conclusively establish their authority therefor from the Company and the approval and ratification by the Company of the papers and documents so executed and the action so taken; and further

RESOLVED, that the Authorized Persons be, and they hereby are, authorized and directed to take any and all further action in connection therewith, including the execution and filing of such amendment or amendments, supplement or supplements and exhibit or exhibits thereto as they may deem necessary or desirable.

The Chairman indicated to the meeting that it may be desirable that the Debt Securities be listed on the New York Stock Exchange and in connection with any such application, to register the Debt Securities under the Securities Exchange Act of 1934, as amended.

Thereupon, it was, on motion duly made and seconded, unanimously

RESOLVED, that the Authorized Persons be, and they hereby are, authorized, in their discretion, to make one or more applications, on behalf of this Company, to the New York Stock Exchange for the listing of up to $375,000,000 aggregate principal amount of Debt Securities; and further

RESOLVED, that Susan Tomasky, Stephen P. Smith, and Stephan T. Haynes, or any one of them, be, and they hereby are, designated to appear before the New York Stock Exchange with full authority to make such changes in any such application or any agreements relating thereto as may be necessary or advisable to conform with the requirements for listing; and further

RESOLVED, that the Authorized Persons be, and they hereby are, authorized to execute and file, on behalf of this Company, one or more applications for the registration of up to $375,000,000 aggregate principal amount of Debt Securities with the SEC pursuant to the provisions of the Securities Exchange Act of 1934, as amended, in such form as the officers of this Company executing the same may determine; and further

RESOLVED, that the Authorized Persons (as previously defined) and the Secretary or an Assistant Secretary be, and each of them hereby is, authorized, in the event any said application for listing is made, to execute and deliver on behalf of this Company an indemnity agreement in such form, with such changes therein as the Authorized Persons executing the same may approve, their execution to be conclusive evidence of such approval; and further

RESOLVED, that the Authorized Persons be, and each of them hereby is, authorized to take any other action and to execute any other documents that in their judgment may be necessary or desirable in connection with listing the Debt Securities on the New York Stock Exchange.

The Chairman further stated that, in connection with the filing with the SEC of one or more Registration Statements relating to the proposed issuance and sale of up to $375,000,000 of Debt Securities, there was to be filed with the SEC a Power of Attorney, dated February 28, 2006, executed by the officers and directors of this Company appointing true and lawful attorneys to act in connection with the filing of such Registration Statement(s) and any and all amendments thereto.

Thereupon, on motion duly made and seconded, the following preambles and resolutions were unanimously adopted:

WHEREAS, the Company proposes to file with the SEC one or more Registration Statements for the registration pursuant to the applicable provisions of the Securities Act of 1933, as amended, of up to $375,000,000 aggregate principal amount of Debt Securities, in one or more new series, each series to have a maturity of not more than 60 years; and

WHEREAS, in connection with said Registration Statement(s), there is to be filed with the SEC a Power of Attorney, dated February 28, 2006, executed by certain of the officers and directors of this Company appointing Michael G. Morris, Susan Tomasky, Stephen P. Smith and Stephan T. Haynes, or any one of them, their true and lawful attorneys, with the powers and authority set forth in said Power of Attorney;

NOW, THEREFORE, BE IT

RESOLVED, that each and every one of said officers and directors be, and they hereby are, authorized to execute said Power of Attorney; and further

RESOLVED, that any and all action hereafter taken by any of said named attorneys under said Power of Attorney be, and the same hereby is, ratified and confirmed and that said attorneys shall have all the powers conferred upon them and each of them by said Power of Attorney; and further

RESOLVED, that said Registration Statement(s) and any amendments thereto, hereafter executed by any of said attorneys under said Power of Attorney be, and the same hereby are, ratified and confirmed as legally binding upon this Company to the same extent as if the same were executed by each said officer and director of this Company personally and not by any of said attorneys.

The Chairman advised the meeting that it was proposed to designate independent counsel for the successful bidder or bidders and/or agents of the Company for the new series of Debt Securities proposed to be issued and sold in connection with the proposed financing program of the Company.

Thereupon, on motion duly made and seconded, it was unanimously

RESOLVED, that Dewey Ballantine LLP be, and said firm hereby is, designated as independent counsel for the successful bidder or bidders and/or agents of the Company for the new series of Debt Securities of this Company proposed to be issued and sold in connection with the proposed financing program of this Company.

The Chairman stated that it may be desirable to enter into one or more hedge agreements, including but not limited to a forward starting swap, treasury lock agreement, treasury put option or interest rate collar agreement ("Hedge Agreement") to protect against future interest rate movements in connection with the issuance of the Debt Securities. He recommended that the Board authorize the appropriate persons to enter into one or more Hedge Agreements, provided that the amount covered by any Hedge Agreement is consistent with the approved AEP Interest Rate Risk Policy and any applicable regulatory orders.

Thereupon, it was, on motion duly made and seconded, unanimously

RESOLVED, that the Authorized Persons (as previously defined) be, and each of them hereby is, authorized to execute and deliver in the name and on behalf of this Company, one or more Hedge Agreements in such form as shall be approved by the Authorized Persons executing the same, such execution to be conclusive evidence of such approval, provided that that the amount covered by any Hedge Agreement is consistent with the approved AEP Interest Rate Risk Policy and any applicable regulatory orders; and further

RESOLVED, that the Authorized Persons be, and they hereby are, authorized to execute and deliver such other documents and instruments, and to do such other acts and things, that in their judgment may be necessary or desirable in connection with the transactions authorized in the foregoing resolutions.

The Chairman stated that it may be desirable to enter into one or more interest rate management agreements, such as interest rate swaps, caps, collars, floors, options, or hedging products such as forwards or futures, or similar products ("Interest Rate Management Agreements"), in each case to manage and minimize interest costs. The transactions will be for a fixed period, and a stated principal amount and may be for underlying fixed or variable obligations of the Company. He recommended that the Board authorize the appropriate persons of the Company to enter into one or more Interest Rate Management Agreements, provided that any such Interest Rate Management Agreement shall conform to the approved AEP Interest Rate Risk Policy and any conditions that may be imposed by any regulatory body.

Thereupon, it was, on motion duly made and seconded, unanimously

RESOLVED, that the Authorized Persons (as previously defined) be, and each of them hereby is, authorized to execute and deliver in the name and on behalf of this Company, one or more Interest Rate Management Agreements in such form as shall be approved by the Authorized Person executing the same, such execution to be conclusive evidence of such approval, provided that any such Interest Rate Management Agreement shall conform to the approved AEP Interest Rate Risk Policy and any conditions that may be imposed by any regulatory body; and further

RESOLVED, that the Authorized Persons of the Company be, and they hereby are, authorized to execute and deliver such other documents and instruments, and to do such other acts and things, that in their judgment may be necessary or desirable in connection with the transactions authorized in the foregoing resolutions.

The Chairman explained that, with respect to the issuance of up to $375,000,000 of Debt Securities through one or more agents under a medium term note program, the Company could enter into a Selling Agency Agreement. He recommended that the Board authorize the appropriate persons to enter into such Selling Agency Agreement with securities dealers yet to be determined.

Thereupon, upon motion duly made and seconded, it was unanimously

RESOLVED, that the Authorized Persons (as previously defined) be, and each of them hereby is, authorized to execute and deliver in the name and on behalf of this Company, a Selling Agency Agreement with such securities dealers in such form as shall be approved by the Authorized Person executing the same, such execution to be conclusive evidence of such approval; and further

The Chairman next explained that the Company could also enter into an Underwriting Agreement ("Underwriting Agreement") with certain underwriters, under which the underwriters may purchase up to $375,000,000 aggregate principal amount of Debt Securities. He recommended that the Board authorize the appropriate persons to enter into an Underwriting Agreement and determine the purchase price of the Debt Securities,

provided that the price shall not be less than 95% (including compensation to the underwriters) of the aggregate principal amount of the Debt Securities.

Thereupon, it was, on motion duly made and seconded, unanimously

RESOLVED, that the Authorized Persons of this Company be, and each of them hereby is, authorized to execute and deliver in the name and on behalf of this Company, an Underwriting Agreement in such form as shall be approved by the person executing the same, such execution to be conclusive evidence of such approval, provided that the purchase price of the Debt Securities shall not be less than 95% (including compensation to the underwriters) of the aggregate principal amount of the Debt Securities; and further

The Chairman explained that the Company may issue and sell unsecured notes ("Notes"), which may include a put option or call option or both pursuant to a Selling Agency Agreement, an Underwriting Agreement or other agreement. He further noted that, in order to enable the Company to perform its obligations under the Selling Agency Agreement, the Underwriting Agreement or other agreement approved at this meeting providing for the sale of up to $375,000,000 aggregate principal amount of the Notes, it was necessary that the Board authorize the execution and delivery of one or more Company Orders or Supplemental Indentures to the Indenture, dated as of November 1, 2000, between the Company and The Bank of New York (the "Indenture"), in such form as shall be approved by the person executing the same, such execution to be conclusive evidence of such approval. Alternately, the Notes may be issued under a new indenture. The terms of each series of Notes will be established under a Company Order or a Supplemental Indenture. The interest rate, maturity and certain other terms have not yet been determined. The Chairman recommended that the Board authorize the appropriate officers of the Company to determine the financial terms and conditions of the Notes, including, without limitation, (i) the principal amount of the Notes to be sold in each offering; (ii) the interest or method of determining the interest on the Notes; (iii) the maturity (which shall not exceed 60 years from the date of issuance) and redemption provisions of the Notes; and (iv) such other terms and conditions as are contemplated or permitted by the Indenture, a Company Order or a Supplemental Indenture. Any fixed interest rate applicable to the Notes would not exceed by more than 4.0% of the yield to maturity of United States Treasury obligations of comparable maturity at the time of pricing

of the Notes. Any initial fluctuating interest rate applicable to the Notes would not exceed 10%.

Thereupon, it was, on motion duly made and seconded, unanimously

RESOLVED, that the Authorized Persons (as previously defined) and the Secretary or Assistant Secretary of the Company be, and they hereby are, authorized to create up to $375,000,000 aggregate principal amount of Notes to be issued under the Indenture and one or more Supplemental Indentures or Company Orders, in such form as shall be approved by the Authorized Person and the Secretary or an Assistant Secretary of the Company executing the same, such execution to be conclusive evidence of such approval, and with such financial terms and conditions as determined by the Authorized Persons, pursuant to the Indenture and one or more Supplemental Indentures or Company Orders, and with either a fixed rate of interest which would not exceed by more than 4.0% of the yield to maturity of United States Treasury obligations of comparable maturity at the time of pricing of the Notes or at an initial fluctuating rate of interest which at the time of pricing would not exceed 10%, or at a combination of such described fixed or fluctuating rates, and to specify the maturity, redemption or tender provisions and other terms, at the time of issuance thereof with the maturity not to exceed 60 years; and further

RESOLVED, that the Authorized Persons and the Secretary or an Assistant Secretary of the Company be, and they hereby are, authorized and directed to execute and deliver, on behalf of this Company, one or more Supplemental Indentures or Company Orders, specifying the designation, terms, redemption provisions and other provisions of the Notes and providing for the creation of each series of Notes, in such form as shall be approved by the Authorized Person and the Secretary or an Assistant Secretary of the Company executing the same, such execution to be conclusive evidence of such approval; that The Bank of New York is hereby requested to join in the execution of any Supplemental Indenture or Company Order, as Trustee; and further

RESOLVED, that the Authorized Persons and the Secretary or an Assistant Secretary of this Company be, and they hereby are, authorized and directed to execute and deliver, on behalf of this Company, to the extent not determined in a Supplemental Indenture or Company Order, a certificate requesting the authentication and delivery of any such Notes and establishing the terms of any tranche of such series or specifying procedures for doing so in accordance with the procedures established in the Indenture; and further

RESOLVED, that the Authorized Persons and the Secretary or an Assistant Secretary of the Company be, and they hereby are, authorized and directed to execute in accordance with the provisions of the Indenture (the signatures of such Authorized Persons and the Secretary or an Assistant Secretary of the Company to be effected either manually or by facsimile, in which case such facsimile is hereby adopted as the signature of such officer thereon), and to deliver to The Bank of New York, as Trustee under the Indenture, the Notes in the aggregate principal amount of up to $375,000,000 as definitive fully registered bonds without coupons in such denominations as may be permitted under the Indenture; and further

RESOLVED, that if any Authorized Persons and the Secretary or an Assistant Secretary of the Company who signs, or whose facsimile signature appears upon, any of the Notes ceases to be such an Authorized Persons and the Secretary or an Assistant Secretary of the Company prior to their issuance, the Notes so signed or bearing such facsimile signature shall nevertheless be valid; and further

RESOLVED, that, subject as aforesaid, The Bank of New York, as such Trustee, be, and it hereby is, requested to authenticate, by the manual signature of an authorized officer of such Trustee, the Notes and to deliver the same from time to time in accordance with the written order of this Company signed in the name of this Company by an Authorized Person and the Secretary or Assistant Secretary of the Company; and further

RESOLVED, that Thomas G. Berkemeyer of Hilliard, Ohio, Ann B. Graf of Columbus, Ohio, David C. House of Lewis Center, Ohio, and William E. Johnson of Gahanna, Ohio, attorneys and employees of American Electric Power Service Corporation, an affiliate of this Company, be, and each of them hereby is, appointed Counsel to render any Opinion of Counsel required by the Indenture in connection with the authentication and delivery of the Notes; and further

RESOLVED, that the office of The Bank of New York, 101 Barclay Street, in the Borough of Manhattan, The City of New York, be, and it hereby is, designated as the office or agency of this Company, in accordance with the Indenture, for the payment of the principal of and the interest on the Notes, for the registration, transfer and exchange of Notes and for notices or demands to be served on the Company with respect to the Notes; and further

RESOLVED, that said The Bank of New York, be, and it hereby is, appointed the withholding agent and attorney of this Company for the purpose of withholding any and all taxes required to be withheld by the Company under the Federal revenue acts from time to time in force and the Treasury Department regulations pertaining thereto, from interest paid from time to time on the Notes, and is hereby authorized and directed to make any and all payments and reports and to file any and all returns and accompanying certificates with the Federal Government which it may be permitted or required to make or file as such agent under any such revenue act and/or Treasury Department regulation pertaining thereto; and further

RESOLVED, that the Authorized Persons and the Secretary or an Assistant Secretary of the Company be, and they hereby are, authorized and directed to effect transfers and exchanges of the Notes, pursuant to the Indenture without charging a sum for any Note issued upon any such transfer or exchange other than a charge in connection with each such transfer or exchange sufficient to cover any tax or other governmental charge in relation thereto; and further

RESOLVED, that The Bank of New York be, and it hereby is, appointed as Note Registrar in accordance with the Indenture; and further

RESOLVED, that the Authorized Persons and the Secretary or an Assistant Secretary of the Company be, and they hereby are, authorized and directed to execute such instruments and papers and to do any and all acts as to them may seem necessary or desirable to carry out the purposes of the foregoing resolutions.

The Chairman further stated that it would be desirable to authorize the proper persons of the Company, on behalf of the Company, to issue one or more unsecured promissory notes to American Electric Power Company, Inc. ("AEP") in an aggregate principal amount of up to $375,000,000 on such terms as are consistent with (i) its financing authority granted by the Oklahoma Corporation Commission and (ii) any applicable rules of the Federal Energy Regulatory Commission ("FERC").

Thereupon, upon motion duly made and seconded, it was unanimously

RESOLVED, that the Authorized Persons of this Company be, and each of them hereby is, authorized, in the name and on behalf of this Company, to borrow from AEP up to $375,000,000, upon such terms as are consistent with (i) the financing authority granted by the Oklahoma Corporation Commission.

The Chairman then stated that one or more insurance companies or other institutions may insure the payment of principal and interest on certain types of Debt Securities as such payments become due or provide other methods of credit enhancement pursuant to a financial guaranty insurance or other policy or agreement ("Insurance Policy"). In this connection, the Company proposes to enter into one or more Insurance Agreements, in such form (including any fees or premiums paid to any such insurance company) as shall be approved by the person executing the same, such execution to be conclusive evidence of such approval.

Thereupon, after discussion, on motion duly made and seconded, it was unanimously

RESOLVED, that in order to enhance the credit of one or more series of Debt Securities, the Authorized Persons (as defined above) be, and they hereby are, authorized to execute and deliver on behalf of the Company one or more Insurance Agreements with an insurance company or other institution of their choice, in such form (including any fees or premiums paid to any such insurance company) as shall be approved by the Authorized Persons executing the same, such execution to be conclusive evidence of such approval; and further

RESOLVED, that the Authorized Persons of the Company be, and they hereby are, authorized on behalf of the Company to take such further action and do all other things that any one of them shall deem necessary or appropriate in connection with, the Insurance Policy and the Insurance Agreement.

EXHIBIT 25

FORM T-1

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

STATEMENT OF ELIGIBILITY

UNDER THE TRUST INDENTURE ACT OF 1939 OF A

CORPORATION DESIGNATED TO ACT AS TRUSTEE

CHECK IF AN APPLICATION TO DETERMINE

ELIGIBILITY OF A TRUSTEE PURSUANT TO

SECTION 305(b)(2) |__|

THE BANK OF NEW YORK

(Exact name of trustee as specified in its charter)

New York (State of incorporation if not a U.S. national bank)	13-5160382 (I.R.S. employer identification no.)
One Wall Street, New York, N.Y. (Address of principal executive offices)	10286 (Zip code)

Public Service Company of Oklahoma

(Exact name of obligor as specified in its charter)

Oklahoma (State or other jurisdiction of incorporation or organization)	73-0410895 (I.R.S. employer identification no.)
1 Riverside Plaza, Columbus, OH (Address of principal executive offices)	43215-2372 (Zip code)

_____________

Senior Notes

(Title of the indenture securities)

1.	General information. Furnish the following information as to the Trustee:

(a)

Name and address of each examining or supervising authority to which it is subject.

Name	Address
Superintendent of Banks of the State of New York	2 Rector Street New York, N.Y. 10006 and Albany, N.Y. 12203
Federal Reserve Bank of New York	33 Liberty Plaza, New York, N.Y. 10045
Federal Deposit Insurance Corporation	Washington, D.C. 20429
New York Clearing House Association	New York, N. Y. 10005

(b)

Whether it is authorized to exercise corporate trust powers.

Yes.

2.	Affiliations with Obligor.

If the obligor is an affiliate of the trustee, describe each such affiliation.

None.

3.	List of Exhibits.

Exhibits identified in parentheses below, on file with the Commission, are incorporated herein by reference as an exhibit hereto, pursuant to Rule 7a-29 under the Trust Indenture Act of 1939 (the "Act") and 17 C.F.R. 229.10(d).

A copy of the Organization Certificate of The Bank of New York (formerly Irving Trust Company) as now in effect, which contains the authority to commence business and a grant of powers to exercise corporate trust powers. (Exhibit 1 to Amendment No. 1 to Form T-1 filed with Registration Statement No. 33-6215, Exhibits 1a and 1b to Form T-1 filed with Registration Statement No. 33-21672 and Exhibit 1 to Form T-1 filed with Registration Statement No. 33-29637.)

2.	A copy of the existing By-laws of the Trustee. (Exhibit 4 to Form T-1 filed with Registration Statement No. 33-31019.)

3.	The consent of the Trustee required by Section 321(b) of the Act. (Exhibit 6 to Form T-1 filed with Registration Statement No. 33-44051.)

4.	A copy of the latest report of condition of the Trustee published pursuant to law or to the requirements of its supervising or examining authority.

SIGNATURE

Pursuant to the requirements of the Act, the Trustee, The Bank of New York, a corporation organized and existing under the laws of the State of New York, has duly caused this statement of eligibility to be signed on its behalf by the undersigned, thereunto duly authorized, all in The City of New York, and State of New York, on the 5 ^th day of April, 2006

THE BANK OF NEW YORK

By: /s/ ROBERT A. MASSIMILLO

Name: ROBERT A. MASSIMILLO

Title: VICE PRESIDENT

EXHIBIT 4 to EXHIBIT 25

Consolidated Report of Condition of

THE BANK OF NEW YORK

of One Wall Street, New York, N.Y. 10286

And Foreign and Domestic Subsidiaries,

a member of the Federal Reserve System, at the close of business December 31, 2005, published in accordance with a call made by the Federal Reserve Bank of this District pursuant to the provisions of the Federal Reserve Act.

ASSETS	Dollar Amounts In Thousands
Cash and balances due from depository institutions:
Noninterest-bearing balances and currency and coin	$	3,361,000
Interest-bearing balances		7,528,000
Securities:
Held-to-maturity securities		1,977,000
Available-for-sale securities		22,664,000
Federal funds sold and securities purchased under agreements to resell
Federal funds sold in domestic offices		809,000
Securities purchased under agreements to resell		309,000
Loans and lease financing receivables:
Loans and leases held for sale		0
Loans and leases, net of unearned income		33,263,000
LESS: Allowance for loan and lease losses		408,000
Loans and leases, net of unearned income and allowance		32,855,000
Trading assets		5,625,000
Premises and fixed assets (including capitalized leases)		821,000
Other real estate owned		0
Investments in unconsolidated subsidiaries and associated companies		283,000
Customers’ liability to this bank on acceptances outstanding		117,000
Intangible assets:
Goodwill		2,138,000
Other intangible assets		764,000
Other assets		6,617,000
Total assets	$	85,868,000
LIABILITIES
Deposits:
In domestic offices	$	38,100,000
Noninterest-bearing		18,123,000
Interest-bearing		19,977,000
In foreign offices, Edge and Agreement subsidiaries, and IBFs		27,218,000
Noninterest-bearing		383,000
Interest-bearing		26,835,000
Federal funds purchased and securities sold under agreements to repurchase
Federal funds purchased in domestic offices .		844,000
Securities sold under agreements to repurchase		118,000
Trading liabilities		2,555,000
Other borrowed money: (includes mortgage indebtedness and obligations under capitalized leases)		1,327,000
Not applicable
Bank’s liability on acceptances executed and outstanding		119,000
Subordinated notes and debentures		1,955,000
Other liabilities		5,119,000
Total liabilities	$	77,355,000
Minority interest in consolidated subsidiaries		139,000
EQUITY CAPITAL
Perpetual preferred stock and related surplus		0
Common stock		1,135,000
Surplus (exclude all surplus related to preferred stock)		2,097,000
Retained earnings		5,256,000
Accumulated other comprehensive income		-114,000
Other equity capital components		0
Total equity capital		8,374,000
Total liabilities, minority interest, and equity capital	$	85,868,000

I, Thomas J. Mastro, Executive Vice President and Comptroller of the above-named bank do hereby declare that this Report of Condition is true and correct to the best of my knowledge and belief.

Thomas J. Mastro,

Executive Vice President and Comptroller

We, the undersigned directors, attest to the correctness of this statement of resources and liabilities. We declare that it has been examined by us, and to the best of our knowledge and belief has been prepared in conformance with the instructions and is true and correct.

Thomas A. Renyi

Gerald L. Hassell

Directors