Exhibit 10.1

ONEOK, INC.

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

(Terminated and Frozen December 31, 2004)

ONEOK, INC. SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

Table of Contents

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ONEOK, INC. SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

PURPOSE

The purpose of the ONEOK, Inc. Supplemental Executive Retirement Plan is to provide the specified benefits to a select group of management and highly compensated employees who contribute materially to the continued growth, development and future business success of ONEOK, Inc., and its subsidiaries. It is the intention of ONEOK, Inc. that the Plan and the particular benefits provided to individuals hereunder be administered as an unfunded deferred compensation and excess benefit plans established and maintained for a select group of management or highly compensated employees.

This Plan is an amendment, restatement, and continuation of the Supplemental Executive Retirement Plan for Employees of ONEOK, Inc. This Amended and Restated Plan replaces all prior documents and amendments and is effective as of the date determined by the Board of Directors.

ARTICLE I.

DEFINITIONS AND CONSTRUCTION

(a) An acquisition (other than directly from the Company) of any voting securities of the Company (the “Voting Securities”) by any “Person” (as the term person is used for purposes of Section 13(d) or 14(d) of the Exchange Act), immediately after which such Person has “Beneficial Ownership” (within the meaning of Rule 13d-3 promulgated under the Exchange Act) of twenty percent (20%) or more of the then outstanding Shares or the combined voting power of the Company’s then outstanding Voting Securities; provided, however, in determining whether a Change in Control has occurred pursuant to this Section 1.1(D), Shares or Voting Securities which are acquired in a “Non-Control Acquisition” (as hereinafter defined) shall not constitute an acquisition which

would cause a Change in Control. A “Non-Control Acquisition” shall mean an acquisition by (i) an employee benefit plan (or a trust forming a part thereof) maintained by (A) the Company or (B) any company or other Person of which a majority of its voting power or its voting equity securities or equity interest is owned or controlled, directly or indirectly, by the Company (for purposes of this definition, a “Related Entity”), (ii) the Company or any Related Entity, or (iii) any Person in connection with a “Non-Control Transaction” (as hereinafter defined);

(b) The individuals who, as of November 15, 2001, are members of the Board of Directors (the “Incumbent Board”), cease for any reason to constitute at least a majority of the members of the Board of Directors; or, following a Merger which results in a Parent Company, the board of directors of the ultimate Parent Company; provided, however , that if the election, or nomination for election by the Company’s common stockholders, of any new director was approved by a vote of at least two-thirds of the Incumbent Board, such new director shall, for purposes of this Plan, be considered as a member of the Incumbent Board; provided further, however , that no individual shall be considered a member of the Incumbent Board if such individual initially assumed office as a result of either an actual or threatened “Election Contest” (as described in Rule 14a-11 promulgated under the Exchange Act) or other actual or threatened solicitation of proxies or consents by or on behalf of a Person other than the Board of Directors (a “Proxy Contest”), including by reason of any agreement intended to avoid or settle any Election Contest or Proxy Contest; or

(c) The consummation of:

(i) A merger, consolidation or reorganization with or into the Company or in which securities of the Company are issued (a “Merger”), unless such Merger is a “Non-Control Transaction.” A “Non-Control Transaction” shall mean a Merger where:

(A) the stockholders of the Company, immediately before such Merger, own directly or indirectly immediately following such Merger at least fifty percent (50%) of the combined voting power of the outstanding voting securities of (x) the company resulting from such Merger (the “Surviving Company”) if fifty percent (50%) or more of the combined voting power of the then outstanding voting securities of the Surviving Company is not Beneficially Owned, directly or indirectly by another Person (a “Parent Company”), or (y) if there is one or more Parent Companies, the ultimate Parent Company;

(B) the individuals who were members of the Incumbent Board immediately prior to the execution of the agreement providing for such Merger constitute at least a majority of the members of the board of directors of (x) the Surviving

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Company, if there is no Parent Company, or (y) if there is one or more Parent Companies, the ultimate Parent Company; and

(C) no Person other than (1) the Company, (2) any Related Entity, (3) any employee benefit plan (or any trust forming a part thereof) that, immediately prior to such Merger was maintained by the Company or any Related Entity, or (4) any Person who, immediately prior to such Merger had Beneficial Ownership of thirty percent (30%) or more of the then outstanding Voting Securities or Shares, has Beneficial Ownership of thirty percent (30%) or more of the combined voting power of the outstanding voting securities or common stock of (x) the Surviving Company if there is no Parent Company, or (y) if there is one or more Parent Companies, the ultimate Parent Company.

(ii) A complete liquidation or dissolution of the Company; or

(iii) The sale or other disposition of all or substantially all of the assets of the Company to any Person (other than a transfer to a Related Entity or under conditions that would constitute a Non-Control Transaction with the disposition of assets being regarded as a Merger for this purpose or the distribution to the Company’s stockholders of the stock of a Related Entity or any other assets).

Notwithstanding the foregoing:

(A) A Change in Control shall not be deemed to occur solely because any Person (the “Subject Person”) acquired Beneficial Ownership of more than the permitted amount of the then outstanding Shares or Voting Securities if: (1) such acquisition occurs as a result of the acquisition of Shares or Voting Securities by the Company which, by reducing the number of Shares or Voting Securities then outstanding, increases the proportional number of shares Beneficially Owned by the Subject Person, provided that if a Change in Control would occur (but for the operation of this subparagraph) as a result of the acquisition of Shares or Voting Securities by the Company, and after such share acquisition by the Company, the Subject Person becomes the Beneficial Owner of any additional Shares or Voting Securities which increases the percentage of the then outstanding Shares or Voting Securities Beneficially Owned by the Subject Person, then a Change in Control shall occur, or (2) (a) within five business days after a Change in Control would have occurred (but for the operation of this subparagraph), or if the Subject Person acquired Beneficial Ownership of twenty percent (20%) or more of the then outstanding Shares or the combined voting power of the

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Company’s then outstanding Voting Securities inadvertently, then after the Subject Person discovers or is notified by the Company that such acquisition would have triggered a Change in Control (but for the operation of this subparagraph), the Subject Person notifies the Board of Directors that it did so inadvertently, and (b) within two business days after such notification, the Subject Person divests itself of a sufficient number of Shares or Voting Securities so that the Subject Person is the Beneficial Owner of less than twenty percent (20%) of the then outstanding Shares or the combined voting power of the Company’s then outstanding Voting Securities.

(B) A Change in Control shall not be deemed to occur if (1) the Shareholder Group (as defined in the Shareholder Agreement) acquires Beneficial Ownership of fifteen percent (15%) or more of the Company’s Voting Securities pursuant to the terms of the Shareholder Agreement, by and between WAI, Inc. (now known as ONEOK, Inc.) and Western Resources, Inc. dated as of November 26, 1997 (the “Shareholder Agreement”), until the earlier of (a) the termination of the Shareholder Agreement or (b) the successful consummation of a Buyout Tender Offer as defined in Section 3.6(b) of the Shareholder Agreement, but upon either of such events, the acquisition or existence of such percentage of Beneficial Ownership by Western Resources, Inc. or any of its affiliates shall constitute a Change in Control or (2) the equity securities of the Company owned by the Shareholder Group are in any manner restructured with the approval of a majority of the members of the Incumbent Board (excluding Shareholder Nominees, as defined in the Shareholder Agreement).

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(a) is totally disabled so as to be prevented from any comparable employment with the Company, including a disability resulting from an occupational cause; and

(b) will be disabled permanently.

The Plan is intended to be an unfunded deferred compensation and excess benefit plan established and maintained for a select group of management and highly compensated employees of the Company within the meaning of Sections 201(2) and (7), 301(a)(3), (9) and 401(a)(1) of ERISA, and shall be construed, interpreted and administered in accordance with such intended purpose.

ARTICLE II.

ELIGIBILITY AND PARTICIPATION

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ARTICLE III.

DEATH BENEFIT

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ARTICLE IV.

RETIREMENT BENEFIT

If an executed Plan Agreement by and between the Participant and the Company does not state or specify a different amount, form and time of payment of a Participant’s Retirement Benefit, then the Participant shall be entitled to receive a Retirement Benefit in accordance with Section 4.1.A and Section 4.1.B, below.

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The Retirement Benefit payment shall commence on the first day of the month following the Participant’s Retirement. Provided, however, Retirement Benefit payments shall not commence until the later of (i) the Participant attaining the age of fifty (50), and (ii) the commencement of retirement benefit payments to the Participant under the Retirement Plan.

(2) Adjustment of Retirement Benefit Payments; Early Commencement . The amount of a Participant’s Retirement Benefit payments will be reduced by reason of early retirement and commencement of payment thereof, based on the following table depending upon the Participant’s age when Retirement Benefit payments to the Participant commence:

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If a Participant attains age sixty-five (65) prior to his/her Retirement, and prior to January 1, 2005, then such Participant shall be 100% vested regardless of the above schedule. A Participant first attaining age sixty-five (65) after December 31, 2004, shall not result in 100% vesting nor otherwise change the vesting and nonforfeitability of the Participant’s Retirement Benefit under the Plan. Retirement Benefits hereunder offsetting the limitations of Internal Revenue Code Sections 401(a)(17) and 415(b) shall be immediately fully vested for all purposes.

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ARTICLE V.

BENEFICIARY

A Participant shall designate a Beneficiary to receive benefits under the Plan and the Participant’s Plan Agreement by completing the appropriate space in such Plan Agreement. If more than one Beneficiary is named, the shares and/or precedence of each Beneficiary shall be indicated. As a condition to any married Participant designating a Beneficiary other than such Participant’s spouse, the Committee may require the spouse’s consent. A Participant shall have the right to change the Beneficiary by submitting to the Committee a Change of Beneficiary in the form attached as Appendix II hereof; provided , however , that no change of Beneficiary shall be effective until acknowledged in writing by the Committee. If the Company has any doubt as to the proper Beneficiary to receive payments hereunder, the Company shall have the right to withhold such payments until the matter is finally adjudicated. Any payment made or caused to be made by the Company in good faith and in accordance with the provisions of the Plan and a Participant’s Plan Agreement shall fully discharge the Company from all further obligations with respect to such payment.

ARTICLE VI.

LEAVE OF ABSENCE

If a Participant is authorized by the Company for any reason, including military, medical, or other, to take a leave of absence from employment, such Participant’s Plan Agreement shall remain in effect.

ARTICLE VII.

SOURCE OF BENEFITS

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Such funding may be in the form of single premium annuities, or an amount sufficient for the trustee to purchase single premium annuities, or life insurance policies or contracts insuring the lives of Plan Participants, from qualified and financially sound insurance companies, and such other forms or types of investments the Company may select from time to time to provide the applicable vested Retirement Benefits payable under the Plan

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and Plan Agreements. Such funding and the purchase of insurance, if any, will not relieve the Company of its obligations to pay or cause to be paid the benefits hereunder.

The Rabbi Trust may be maintained and administered to also provide for the funding of payment of amounts payable to participants in other deferred compensation and benefit plans of the Company. The funding, investments and administration of the Rabbi Trust in connection with such other separate plan or plans shall be separately administered and accounted for as determined to be necessary and appropriate by the Company and trustee pursuant to the terms of the Rabbi Trust. It shall be permissible for the trustee to invest funds of the Rabbi Trust in one or more forms of investment that is common to plans being funded thereunder.

The Rabbi Trust shall be a grantor trust of which the Company is the grantor within the meaning of the Code. The principal of the Rabbi Trust and any earnings thereon shall be held separate and apart from other funds of the Company and shall be used exclusively for the uses and purposes of Participants in the Plan and general creditors of the Company as specified hereinbelow and in the trust instrument. Participants in the Plan and their Beneficiaries shall have no preferred claim on, or any beneficial ownership in any assets of the Rabbi Trust; and any rights created under the Plan or Participant Plan Agreements, and the Rabbi Trust are to be made unsecured contractual rights of Participants and their Beneficiaries against the Company; and assets held by the Rabbi Trust will be subject to the claims of the Company’s general creditors under federal and state law in the event of insolvency of the Company.

ARTICLE VIII.

TERMINATION OF EMPLOYMENT

Neither the Plan nor a Participant’s Plan Agreement, either singly or collectively, in any way obligate the Company, or any subsidiary of the Company, to continue the employment of a Participant with the Company, or any subsidiary of the Company, nor does either limit the right of the Company or any subsidiary of the Company at any time and for any reason to terminate the Participant’s employment. Termination of a Participant’s employment with the Company, or any subsidiary of the Company, for any reason, whether by action of the Company, subsidiary, or Participant, shall immediately terminate the Participant’s participation in the Plan and such Participant’s Plan Agreement, and all further obligations of either party thereunder, except as may be provided in Article X and the Participant’s Plan Agreement. In no event shall the Plan or a Plan Agreement, either singly or collectively, by their terms or implications constitute an employment contract of any nature whatsoever between the Company, or any subsidiary, and a Participant.

ARTICLE IX.

TERMINATION OF PARTICIPATION

A Participant reserves the right to terminate participation in the Plan and such Participant’s Plan Agreement at any time by giving the Company written notice of such termination not less than 30 days (i) prior to the anniversary date of any contract or contracts of

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insurance on the life of such Participant which may be in force and utilized by the Company in connection with the Plan, or (ii) prior to the date a Participant selects for termination if no insurance contract is in effect.

ARTICLE X.

TERMINATION, AMENDMENT, MODIFICATION,

OR SUPPLEMENT OF THE PLAN

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ARTICLE XI.

TREATMENT OF BENEFITS

Retirement Benefits under the Plan and Plan Agreements entered into hereunder shall not be considered compensation for the purpose of computing contributions or benefits under any plan maintained by the Company, or any of its subsidiaries, which is qualified under Section 401(a) of the Code.

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ARTICLE XII.

RESTRICTIONS ON ALIENATION OF BENEFITS

No Retirement Benefit, or other right or benefit under the Plan or a Plan Agreement shall be subject to anticipation, alienation, sale, assignment, pledge, encumbrance, or charge, and any attempt to anticipate, alienate, sell, assign, pledge, encumber, or charge the same shall be void. No Retirement Benefit, or right or benefit under the Plan or under any Plan Agreement shall in any manner be liable for or subject to the debts, contracts, liabilities, or torts of the person entitled to such thereto. If any Participant or Beneficiary under the Plan or a Plan Agreement should become bankrupt or attempt to anticipate, alienate, sell, assign, pledge, encumber, or charge any right to a benefit under the Plan or under any Plan Agreement, then such right or benefit shall, in the discretion of the Committee, cease, and in such event, the Committee may hold or apply the same or any part thereof for the benefit of such Participant or Beneficiary, his or her spouse, children, or other dependents, or any of them, in such portion as the Committee, in its sole and absolute discretion, may deem proper.

ARTICLE XIII.

ADMINISTRATION OF THE PLAN

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ARTICLE XIV.

ADOPTION OF PLAN BY SUBSIDIARY,

AFFILIATED OR ASSOCIATED COMPANIES

Any corporation which is a subsidiary of the Company may, with the approval of the Board of Directors, adopt the Plan and thereby come within the definition of Company in Article I hereof.

ARTICLE XV.

EXCESS RETIREMENT BENEFIT PAYMENTS

COMMENCED BEFORE SEPTEMBER 1, 1998

Notwithstanding anything expressed or implied to the contrary herein, the payment of excess retirement benefits to a retired Plan Participant that commenced under the Plan prior to September 1, 1998, shall be paid in accordance with, and to the extent provided by, the applicable terms and provisions of the Plan in effect prior to September 1, 1998.

ARTICLE XVI.

MISCELLANEOUS

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100 West Fifth Street

Tulsa, Oklahoma 74102

and marked to the attention of the Secretary, Supplemental Executive Retirement Plan Administrative Committee; or, if notice to a Participant, addressed to the address shown on such Participant’s most recent employment file with the Company.

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APPENDIX I

ONEOK, INC. SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN AGREEMENT

THE FOLLOWING FORM OF ONEOK, INC. SUPPLEMENTAL EXECUTIVE RETIREMENT AGREEMENT IS A DRAFT MODEL FORM OF AGREEMENT FOR USE BY THE COMPANY AND EACH PLAN PARTICIPANT.

EACH PLAN AGREEMENT BETWEEN THE COMPANY AND A PARTICIPANT EXECUTED UNDER THE PLAN SHALL CONTAIN THE PARTICULAR TERMS AND PROVISIONS AGREED TO BY THE COMPANY AND PARTICIPANT, WHICH MAY DIFFER FROM THE MODEL FORM OF AGREEMENT SHOWN HEREIN. EACH SUCH PLAN AGREEMENT SHALL BE EFFECTIVE AND BE PERFORMED IN ACCORDANCE WITH THE TERMS AND PROVISIONS THEREOF NOTWITHSTANDING ANYTHING TO THE CONTRARY WHICH MAY BE EXPRESSED OR IMPLIED IN THE MODEL FORM OF AGREEMENT SHOWN AS AN EXAMPLE IN THIS APPENDIX I.

I acknowledge that, as an Employee of ONEOK, Inc., I have been offered an opportunity to participate in the ONEOK, Inc. Supplemental Executive Retirement Plan (Plan) described in the attached document (which is incorporated herein by reference), and that I have elected one of the alternatives set forth as indicated by the space which I have checked:

                 To participate in the Plan

                 Not to participate in the Plan

My Retirement Benefit, Disability Benefit, Death Benefit, and commencement of such payments, and designated Beneficiary(ies) are agreed to be as follows:

1.A Retirement Benefit (Article IV of Plan). Subject to Paragraph 2, below, and the vesting schedule in Paragraph 5, below, a monthly amount which, when combined with existing pension benefits payable to me under the Retirement Plan and any retirement plans (other than 401(k) plans) of any of my former employers, will provide the percentage of the highest thirty-six (36) consecutive months average Compensation (or average of all months of Compensation if employed less than thirty-six (36) months) of the last sixty (60) months of Service, for life (15 years minimum) as illustrated below.

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The Retirement Benefit payment shall commence on the first day of the month following my Retirement. Provided, however, Retirement Benefit payments shall not commence until the later of (i) my attaining the age of fifty (50), and (ii) the commencement of retirement benefit payments to me under the Retirement Plan.

1.B Adjustment of Retirement Benefit Payments; Early Commencement . The amount of my Retirement Benefit payments will be reduced by reason of early retirement and commencement of payment thereof, based on the following table depending upon my age when Retirement Benefit payments to me commence:

2. Code Sections 401(a)(17) and 415(b) Limitations . Notwithstanding Paragraphs 1A and 1B above, the Plan and this Plan Agreement shall provide a Retirement Benefit attributable to my annual eligible compensation under the Retirement Plan that is in excess of the limitations on my Retirement Plan benefits contained in Code Sections 401(a)(17) and 415(b). This portion of the Retirement Benefit will be computed by applying the same benefit formula, vesting provisions, and early retirement provisions as are in the Retirement Plan. Any part of the Retirement Benefit provided under this Paragraph 2 will offset and reduce that part of the Retirement Benefit provided under Paragraphs 1A and 1B above.

3. Disability Benefit (Article IV of Plan). If I should suffer a Total and Permanent Disability prior to my Retirement, an amount which, when combined with then existing pension benefits under the Retirement Plan and any retirement plans (other than 401(k) plans) of any of my former employers, will provide sixty-one and 7/10 percent (61.7%) of my highest thirty-six (36) consecutive months average Compensation (or average of all months of Compensation if

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employed less than thirty-six (36) months) of my last sixty (60) months of Service, for life (15 years minimum).

4. Death Benefit . (Article III of Plan). If my death should occur before my Retirement, an amount which, when combined with then existing pension benefits under the Retirement Plan and any retirement plans (other than 401(k) plans) of any of my former employers, will provide fifty percent (50%) (or the vested Retirement Benefit, whichever is greater) of my highest thirty-six (36) consecutive months average Compensation (or average of all months of Compensation if employed less than thirty-six (36) months) of my last sixty (60) months of Service, payable to the Beneficiary for one hundred eighty (180) months following death.

5. Vesting Schedule . The Retirement Benefit payable to me shall unconditionally vest and become nonforfeitable according to the following vesting schedule:

If I attain age sixty-five (65) prior to Retirement, I shall be 100% vested regardless of the above schedule. Retirement Benefits hereunder offsetting the limitations of Internal Revenue Code Sections 401(a)(17) and 415(b) shall be immediately fully vested for all purposes.

6. Beneficiary . I hereby designate as my Primary Beneficiary under the Plan and the Plan Agreement:                                                                                                                                              and, I hereby designate as my Secondary Beneficiary under the Plan and the Plan Agreement:                                                       .

The term “Beneficiary” as used herein shall mean the Primary Beneficiary if such Primary Beneficiary is an individual and such individual shall survive me by at least thirty (30) days, and shall mean the Secondary Beneficiary if such an individual Primary Beneficiary does not survive me by at least thirty (30) days, and shall mean my Estate, if neither Primary nor a Secondary Beneficiary who is an individual survives me by at least thirty (30) days. I shall have the right to change my designation of my Primary and/or Secondary Beneficiary from time to time, in such manner as shall be required by the Company, it being agreed that no change in Beneficiary shall

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be effective until acknowledged in writing by the Committee. (If designation of a Beneficiary is to be irrevocable, strike and initial previous sentence.)

I further acknowledge that neither the Company nor any of its subsidiaries, affiliated companies, officers, employees, or agents has any responsibility whatsoever for the changes which I may make in other personal plans or programs as a result of my decision regarding the Plan and they are fully released to such extent. The Company agrees that although the Plan may be terminated or modified at any time, in the sole discretion of the Company, I shall have those rights which are vested and nonforfeitable under the terms and provisions of this Plan Agreement to the extent such may be applicable to me at the time of such termination.

7. Plan . This Agreement is entered into and executed by me and the Company pursuant to, and as a part of the Plan. Except as otherwise expressly provided in the Plan or this Plan Agreement, the terms and provisions of this Plan Agreement shall control in the event of any conflict between its terms and provisions and the terms of the Plan. It is intended that this Plan Agreement shall specifically state the amount, form and time of payment of my Retirement Benefit, and the vesting schedule to be applicable to my Retirement Benefit. This Plan Agreement shall be construed so as to be performed in a manner consistent with express terms and provisions of the Plan, unless there is a clear and express inconsistency, in which case the terms of this Plan Agreement shall control.

8. Amendment; Termination . No amendment of this Plan Agreement shall be effective unless agreed to in a written document signed by me and the Company. The Company may terminate this Agreement in event of a termination of the Plan; provided, no termination of the Plan and no amendment of the Plan or of this Plan Agreement shall result in a decrease or forfeiture of my vested accrued Retirement Benefit under the Plan and this Plan Agreement as of the date of such termination or amendment, as more particularly provided for under the provisions of Section 10.2 of the Plan on the date of this Plan Agreement.

9. Restriction of Assignment . Except as otherwise expressly provided in this Agreement, I agree on behalf of myself and of my executors and administrators, heirs, legatees, distributees, and any other person or persons claiming any benefits under me under this Agreement, that this Agreement and its rights, interests, and benefits shall not be assigned, transferred, pledged, or hypothecated in any way by me or any executor, administrator, heir, legatee, distributee, or other person claiming under me by virtue of this Agreement, and shall not be subject to execution, attachment, or similar process. Any attempted assignment, transfer, pledge or hypothecation, or other disposition of this Agreement or of such rights, interests, and benefits contrary to the above provisions, or the levy of any such attachment or similar process thereupon, shall be null and void and without effect.

10. Binding Effect . This Agreement shall be binding upon and inure to the benefit of any successor of the Company, and any such successor shall be deemed substituted for the Company under the terms of this Agreement. As used in this Agreement, the term “successor” shall include any person, firm, corporation, or other business entity which at any time, whether by merger, purchase, or otherwise, acquires all or substantially all of the Company’s assets or business.

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11. Entire Agreement . This Agreement supersedes all other agreements previously made between the Company and me relating to its subject matter. There are no other understandings or agreements.

12. Non-Waiver . No delay or failure by either the Company or me in exercising any right under this Agreement, and no partial or single exercise of such right, shall constitute a waiver of that or any other right.

13. Governing Law . Except as otherwise provided by ERISA, this Agreement shall be construed in accordance with and governed by the laws of the State of Oklahoma.

IN WITNESS WHEREOF, ONEOK, Inc. and Plan Participant have executed the Plan Agreement as of                      , 200      .

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APPENDIX II

CHANGE OF BENEFICIARY FORM FOR

ONEOK, INC.

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

I,                                                   , as a Participant in the above Plan, hereby change my Beneficiary Designation for the Plan, and make this my Beneficiary Designation to supercede and replace any and all other prior Beneficiary Designation instruments, as follows:

Primary Beneficiary(ies):

The “Beneficiary” designated to receive my benefits under the Plan shall mean the Primary Beneficiary(ies) designated above, who shall receive the respective share percentage(s) specified above if such Primary Beneficiary(ies) is an individual and survives me by at least thirty (30) days, and if any individual designated as Primary Beneficiary does not so survive me then such Beneficiary’s share shall be received by any other designated Primary Beneficiary(ies) who does so survive me, each in the proportion of such surviving Beneficiary’s share percentage stated above to the total of such stated share percentages of the Primary Beneficiary(ies) who so survive me. If none the Primary Beneficiaries designated above who are individuals so survive me, and there are no other designated Primary Beneficiary(ies) who is not an individual, then my benefits under the Plan shall be received by the Secondary Beneficiaries designated above, who shall receive the respective share percentages specified above if such Secondary Beneficiary (ies) who is an individual survives me by at least thirty (30) days, and if any designated Secondary Beneficiary who is an individual does not so survive me then such Beneficiary’s share shall be received by any other designated Secondary Beneficiary(ies) who does so survive me, proportionately divided in the same manner as is described above with respect to Primary Beneficiaries. I shall have the right to change designation of my Primary Beneficiary(ies) and/or Secondary Beneficiary(ies) from time to time in such manner and on such form as shall be required prescribed by the Company, it being agreed that no change in beneficiary shall be effective until acknowledged in writing by the Committee.

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Signature of the above Participant witnessed this              day of                      ,              , in the presence of:

CONSENT OF SPOUSE

I, the undersigned spouse of the Participant named in the foregoing “Change of Beneficiary Form” hereby certify that I have read the Change of Beneficiary Form and fully understand the property and benefits subject to designation of a beneficiary or beneficiaries is my spouse’s accrued benefit under the Plan, in which I may possess a beneficial interest, provided I survive my spouse. Being fully satisfied with the provisions and effect of the foregoing Change of Beneficiary Form, I hereby consent to and accept the designation of beneficiaries made therein without regard to whether I survive or predecease my spouse. I intend for this consent to be irrevocable and my spouse may make any further changes in the designation of his beneficiary or beneficiaries without my consent.

I have executed this consent this              day of                      .              .

Signature of spouse witnessed this              day of                      .              in the presence of:

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Exhibit 10.2

ONEOK, INC.

2005 SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

January 1, 2005

ONEOK, INC.

2005 SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

Table of Contents

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ONEOK, INC.

2005 SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

PURPOSE

The purpose of the ONEOK, Inc. 2005 Supplemental Executive Retirement Plan is to provide the specified benefits to employees who are in a select group of management or highly compensated employees who contribute materially to the continued growth, development and future business success of ONEOK, Inc., and its subsidiaries, effective January 1, 2005. It is the intention of ONEOK, Inc. that the Plan and the particular benefits provided to individuals hereunder be administered as an unfunded deferred compensation and excess benefit plans established and maintained for a select group of management or highly compensated employees.

This Plan is a new and separate plan, and except as otherwise expressly provided herein, is not a continuation, successor plan to, or an amendment or restatement of the preexisting and separate ONEOK, Inc. Supplemental Executive Retirement Plan, as terminated and frozen pursuant to the terms thereof, effective December 31, 2004 (hereinafter referred to as the “Prior Frozen SERP”). It is intended that no individual shall be entitled to benefit under the both the Prior Frozen SERP and this Plan.

The Plan is intended to meet all requirements of Section 409A of the Code for compensation deferred under the Plan to not be includible in gross income of the Participant until actually paid or distributed pursuant to the Plan.

PART A EXCESS RETIREMENT BENEFITS

ARTICLE I

PURPOSE AND SCOPE OF PART A

The provisions of Part A of the Plan shall establish and provide excess retirement benefits to Employees of the Company who are (i) in a select group of management or highly compensated employees of the Company within the meaning of Sections 201(a)(7), 301(a)(9) and 401(a)(1) of ERISA, and (ii) selected to participate in Excess Retirement Benefits pursuant to the terms and provisions of this Part A of the Plan. The Excess Retirement Benefits provided to participants under Part A of the Plan are separate and independent from Supplemental Retirement Benefits provided under Part B of the Plan.

ARTICLE II

ELIGIBILITY AND PARTICIPATION

In order to be eligible to be selected as a Part A Participant in the Plan pursuant to Section 2.2 of this Article II, below, an Employee must be in a select group of management or highly compensated employees of the Company, as determined by the Chief Executive Officer, or the Committee in the case of the Chief Executive Officer, in the Chief Executive Officer’s (or Committee’s, as applicable)sole and absolute discretion.

An eligible Employee may become a Part A Participant in the Plan only by being selected for participation pursuant to Section 2.2 of this Article II, below.

Provided, that no Employee who is a participant in the Prior Frozen SERP or entitled to receive any benefit or payment under the Prior Frozen SERP shall be selected to be a Part A Participant in the Plan; and it may be made a condition to the selection of an eligible Employee as a Part A Participant that such Employee shall have elected in writing to completely terminate his/her participation in the Prior Frozen SERP and waive all his/her entitlement to any benefit or payment under the Prior Frozen SERP; and notwithstanding anything otherwise provided herein, any eligible Employee who becomes a Part A Participant shall be deemed to consent and agree that his/her participation in Part A of the Plan shall supersede and cancel any entitlement he/she had to any benefit or payment under the Prior Frozen SERP.

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ARTICLE III

EXCESS RETIREMENT BENEFIT

B. Provided, that except in the case of and to the extent of a Key Employee Required Deferral, a Part A Participant shall be entitled to make a Subsequent Election to change the date of distribution and payment of his/her Excess Retirement Benefit from his/her Normal SERP Benefit Commencement Date to the Deferred SERP Benefit Commencement Date resulting from such election, if:

(i) he/she does not commence receiving payment of his/her Retirement Plan Benefit on or before his/her Normal SERP Benefit Commencement Date,

(ii) he/she makes a corresponding Subsequent Election with respect to the Supplemental Retirement Benefit, if any, he/she is entitled to under Part B of the Plan, and

(iii) he/she delivers a written notification of such Subsequent Election to the Committee,  , or its designee, in the form it prescribes, not less than twelve (12) months prior to his/her Normal SERP Benefit Commencement Date.

The Committee, in its discretion, may allow a Part A Participant to make a Subsequent Election as to any Deferred SERP Benefit Commencement Date established for the payment of his/her Excess Retirement Benefit under and subject to the same conditions and requirements as set forth above in this paragraph 3.2.B.

Provided, that notwithstanding the foregoing, a Subsequent Election deferral will always occur pursuant to a Part A Participant’s initial Election in any case in which he/she does not commence receiving his/her Retirement Plan Benefit on his/her Normal SERP Benefit Commencement Date, or on or before a Deferred SERP Benefit Commencement

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Date, in accordance with paragraph D of this Section 3.2, below, notwithstanding that no other written notification is delivered by him/her pursuant to the foregoing provisions.

C. Notwithstanding anything otherwise provided in the Plan or in any Election or Subsequent Election of a Part A Participant, any Subsequent Election made under the Plan shall result in the first payment with respect to which such Subsequent Election is made being deferred for a period of five (5) years from the date such payment would otherwise have been made; the payment and distribution of any Excess Retirement Benefit and any Supplemental Retirement Benefit to which a Part A Participant is entitled under the Plan shall in all cases be made simultaneously; and the payment and distribution of such Excess Retirement Benefit and Supplemental Retirement Benefit shall in no case commence or be made prior to the commencement of payment of such Part A Participant’s Retirement Plan Benefit.

D. Provided, further, that if the payment of the Retirement Plan Benefit to which a Part A Participant is entitled for any reason does not commence on or before his/her Normal SERP Benefit Commencement Date, or a then existing Deferred SERP Benefit Commencement Date established for such Part A Participant under the Plan, then in such event, subject to compliance with all nonqualified deferred compensation plan requirements governing the Plan under Section 3.7, below, such Part A Participant’s initial Election shall be followed and shall be deemed for all purposes to be a Subsequent Election and to change the date of distribution and payment of his/her Excess Retirement Benefit to a subsequent Deferred SERP Benefit Commencement Date resulting from such Subsequent Election.

E. If a Part A Participant does not commence receiving his Retirement Plan Benefit on his Normal SERP Benefit Commencement Date, and a Deferred SERP Benefit Commencement Date is established for the payment of his/her Excess Retirement Benefit, then upon commencement of payment of his/her Excess Retirement Benefit on a Deferred SERP Benefit Commencement Date such Part A Participant shall be entitled to receive an Excess Retirement Benefit Catch-Up Payment on that Deferred SERP Benefit Commencement Date, if an to the extent the payment of his/her Retirement Plan Benefit has commenced prior to such Deferred SERP Benefit Commencement Date.

F. If a Part A Participant is a Key Employee his/her Excess Retirement Benefit shall not commence being paid until after the end of the Key Employee Required Deferral Period. In such a case the Part A Participant shall receive a Key Employee Catch-Up Payment at the end of the Key Employee Required Deferral Period and thereafter receive Excess Retirement Benefit monthly payments in accordance with the Plan.

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A Part A Participant’s initial Election shall include his/her consent and agreement, to all terms and provisions of the Plan with respect to any Subsequent Election and the effect thereof with respect to the time and form of payment of any Excess Retirement Benefit he/she is entitled to receive under the Plan.

ARTICLE IV

BENEFICIARY

The Beneficiary of a Part A Participant’s Excess Retirement Benefit shall be the beneficiary of such Part A Participant’s corresponding Retirement Plan Benefit.

ARTICLE V

LEAVE OF ABSENCE

If a Part A Participant is authorized by the Company for any reason, including military, medical, or other, to take a leave of absence from employment, such Part A Participant’s participation in Part A of the Plan shall remain in effect.

ARTICLE VI

ADMINISTRATION OF PART A OF THE PLAN

Except as otherwise expressly provided herein, this Part A of the Plan shall be administered pursuant to the provisions of Part C of the Plan.

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PART B SUPPLEMENTAL RETIREMENT BENEFITS

ARTICLE I

PURPOSE AND SCOPE OF PART B

The provisions of Part B of the Plan shall establish and provide supplemental retirement benefits to employees who are (i) in a select group of management or highly compensated employees of the Company within the meaning of Sections 201(a)(2), 301(a)(3) and 401(a)(1) of ERISA, (ii) Officers of the Company, and (iii) selected to participate in and receive Supplemental Retirement Benefits pursuant to the terms and provisions of this Part B of the Plan. The Supplemental Retirement Benefits provided to participants under Part B of the Plan are separate and independent from Excess Retirement Benefits provided under Part A of the Plan.

ARTICLE II

ELIGIBILITY AND PARTICIPATION

Provided, that no Employee/Officer, and who is a participant in the Prior Frozen SERP or entitled to receive any benefit or payment under the Prior Frozen SERP shall be selected to be a Part B Participant in the Plan; and it may be made a condition to the selection of an eligible Employee/Officer to be a Part B Participant that he/she shall have elected in writing to completely terminate his/her participation in the Prior Frozen SERP and waive all his/her entitlement to any benefit or payment under the Prior Frozen SERP; and notwithstanding anything otherwise provided herein, any eligible Employee/Officer who becomes a Part B Participant shall be deemed to consent to and agree that his/her

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participation in Part B of the Plan shall supersede and cancel any entitlement he/she had to any benefit or payment under the Prior Frozen SERP.

ARTICLE III

SUPPLEMENTAL RETIREMENT BENEFIT

A. General . Subject to Section 3.1.D. of this Article III, below, the Company shall pay or cause to be paid to such Part B Participant a Supplemental Retirement Benefit, which shall be a monthly amount which when combined with the Retirement Plan Benefit and existing pension benefits payable to the Part B Participant under the Retirement Plan and any retirement plans (other than 401(k) plans) of any of the Part B Participant’s former employers, will be equal to the product of the Part B Participant’s

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Final Average Earnings, multiplied by the Part B Participant’s Benefit Factor Percentage at his/her Retirement under the Table in Section 3.1.B. of this Article III, below, and then multiplied by the Part B Participant’s Service Factor Percentage at his/her Retirement under the Table in Section 3.1.C. of this Article III, below; subject to adjustment and reduction, if applicable, pursuant to Section 3.1.E. of this Article III, below.

If an executed Plan Agreement by and between the Part B Participant and the Company is not executed, or an executed Plan Agreement of a Part B Participant does not state or specify a different amount, form and time of payment of a Part B Participant’s Supplemental Retirement Benefit, then the Part B Participant shall be entitled to receive a Supplemental Retirement Benefit in accordance with this Section 3.1.

B. Benefit Factor Percentage . A Part B Participant’s Benefit Factor Percentage shall be based upon his/her age at his/her Retirement, as follows:

C. Service Factor Percentage . A Part B Participant’s Service Factor Percentage shall be based upon his/her completed Years of Service at his/her Retirement, as follows:

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D. Excess Retirement Benefit Offset . If a Part B Participant is also a Part A Participant under the Plan and entitled to receive an Excess Retirement Benefit under Part A of the Plan, the Supplemental Retirement Benefit of such Part B Participant shall be offset and reduced by an amount equal to such Excess Retirement Benefit, whichever is payable to such Part B Participant pursuant to Part A of the Plan.

E. Adjustment of Retirement Benefit Payments; Early Commencement . The amount of a Part B Participant’s Supplemental Retirement Benefit payments will be reduced by reason of early commencement of payment thereof, based on the following table depending upon the Part B Participant’s age when Supplemental Retirement Benefit payments to the Part B Participant commence:

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B. Provided, that except in the case of and to the extent of a Key Employee Required Deferral, a Part B Participant shall be entitled to make a Subsequent Election to change the date of distribution and payment of his/her Supplemental Retirement Benefit from his/her Normal SERP Benefit Commencement Date to the Deferred SERP Benefit Commencement Date resulting from such election, if :

(i) he/she does not commence receiving his/her Retirement Plan Benefit on or before his/her Normal SERP Benefit Commencement Date,

(ii) he/she makes a corresponding Subsequent Election with respect to the Excess Retirement Benefit, if any, he/she is entitled to under Part A of the Plan, and

(iii) he/she delivers a written notification of such Subsequent Election to the Committee, or its designee, in the form it prescribes, not less than twelve (12) months prior to his/her Normal SERP Benefit Commencement Date.

The Committee, in its discretion, may allow a Part B Participant to make a Subsequent Election as to any Deferred SERP Benefit Commencement Date established for payment of his/her Supplemental Retirement Benefit under and subject to the same conditions and requirements as set forth above in this Section 3.2.B.

Provided, that notwithstanding the foregoing, a Subsequent Election deferral will always occur pursuant to a Part B Participant’s initial Election in any case in which he/she does not commence receiving his/her Retirement Plan Benefit on his/her Normal SERP Benefit Commencement Date, in accordance with such Election and paragraph D, of this Section 3.2., below, notwithstanding that no other written notification is delivered by him/her pursuant to the foregoing provisions.

C. Nothwithstanding anything to the contrary otherwise provided in the Plan or in any Election or Subsequent Election of a Part B Participant, any Subsequent Election made under the Plan shall result in the first payment with respect to which such Subsequent Election is made being deferred to a Deferred SERP Benefit Commencement Date that is for a period of five (5) years from the date such payment would otherwise have been made; the payment and distribution of any Supplemental Retirement Benefit and any Excess Retirement Benefit to which a Part B Participant is entitled under the Plan shall in all cases be made simultaneously; and the payment and distribution of such Supplemental Retirement Benefit and Excess Retirement Benefit shall in no case commence or be made prior to the commencement of payment of such Part B Participant’s Retirement Plan Benefit.

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D. Provided, further, that if the payment of the Retirement Plan Benefit to which a Part B Participant is entitled for any reason does not commence on or before a then existing Deferred SERP Benefit Commencement Date, or a then existing Deferred SERP Benefit Commencement Date established for such Part B Participant under the Plan, then in such event, subject to compliance with all nonqualified deferred compensation plan requirements governing the Plan under Section 3.7, below, such Part B Participant’s initial Election shall be followed and shall be deemed for all purposes to be a Subsequent Election to change the date of distribution and payment of his/her Supplemental Retirement Benefit to a subsequent Deferred SERP Benefit Commencement Date resulting from such Subsequent Election.

E. If a Part B Participant does not commence receiving his Retirement Plan Benefit on his/her Normal SERP Benefit Commencement Date, and a Deferred SERP Benefit Commencement Date is established for the payment of his/her Supplemental Retirement Benefit, then upon commencement of payment of his/her Supplemental Retirement Benefit on his/her Deferred SERP Benefit Commencement Date such Part B Participant shall be entitled to receive a Supplemental Retirement Benefit Catch-Up Payment on that Deferred SERP Benefit Commencement Date, if and to the extent the payment of his/her Retirement Plan Benefit has commenced prior to such Deferred SERP Benefit Commencement Date.

F. If a Part B Participant is a Key Employee his/her Supplemental Retirement Benefit shall not commence being paid until after the end of the Key Employee Required Deferral Period. In such case the Part B Participant shall receive a Key Employee Catch-Up Payment at the end of the Key Employee Required Deferral Period and thereafter receive Supplemental Retirement Benefit monthly payments in accordance with the Plan.

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ARTICLE IV

BENEFICIARY

The Beneficiary of a Part B Participant’s Supplemental Retirement Benefit shall be the beneficiary of such Part B Participant’s Retirement Plan Benefit.

ARTICLE V

SUPPLEMENTAL RETIREMENT BENEFIT ADJUSTMENTS

The Committee shall be authorized to make and apply special adjustments in determining the amount of a Part B Participant’s Supplemental Retirement Benefit. Such adjustments may be made from time to time by the Committee for any Part B Participant, and may include, without limitation, the granting or deemed accrual of additional Years of Service, the waiver of an offset of retirement benefits provided by a prior employer, or such other adjustments as the Committee determines, in its sole discretion; provided, however, that no such adjustment shall be effective until it is made and expressly acknowledged in writing by the Committee.

ARTICLE VI

LEAVE OF ABSENCE

If a Part B Participant is authorized by the Company for any reason, including military, medical, or other, to take a leave of absence from employment, such Part B Participant’s Plan Agreement shall remain in effect.

ARTICLE VII

ADMINISTRATION OF PART B OF THE PLAN

Except as otherwise expressly provided herein, this Part B of the Plan shall be administered pursuant to the provisions of Part C of the Plan.

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PART C

PLAN ADMINISTRATION AND MISCELLANEOUS PROVISIONS

ARTICLE I

PURPOSE AND SCOPE OF PART C

The purpose of Part C of the Plan is to establish and provide certain provisions governing the administration, and interpretation and application of all the provisions of the Plan. Unless otherwise expressly indicated, the terms and provisions of Part C of the Plan shall be applicable to Part A, Part B and Part C of the Plan.

ARTICLE II

DEFINITIONS AND CONSTRUCTION

A. “Base Cash Compensation” shall mean the regular monthly salary paid to a Participant by the Company before any deductions or exclusions for taxes or other purposes, and excluding any vehicle allowance, incentives, commissions and any other special pay.

B. “Beneficiary” shall mean the individual or individuals, or any trust or trusts, or the estate of a Participant entitled to receive any benefits in accordance with the terms of the Plan.

C. “Board of Directors” shall mean the Board of Directors of ONEOK, Inc., unless otherwise indicated or the context otherwise requires.

(A) “Change in Control” shall mean to the extent provided by Treasury Regulations issued under Code Section 409A, a change in the ownership or effective control of the Company, or in the ownership of a substantial portion of the assets of the Company.

D. “Code” shall mean the Internal Revenue Code of 1986, as amended.

E. “Committee” shall mean the Executive Compensation Committee of the Board of Directors or such other Committee appointed to manage and administer the Plan and individual Plan Agreements in accordance with the provisions of Article III of this Part C of the Plan.

F. “Company” shall mean ONEOK, Inc., an Oklahoma corporation, or any division or subsidiary thereof.

G. “Compensation” shall mean the Base and Short-Term Incentive Cash Compensation from the Company paid to or deferred by a Participant during a calendar year.

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H. “Deferred Compensation” shall mean any Excess Retirement Benefit or Supplemental Retirement Benefit to be paid to a Participant pursuant to the Plan.

I. “Deferred Excess Retirement Benefit Payment” shall mean the amount of any monthly Excess Retirement Benefit that is not paid to a Part A Participant for any month during such Part A Participant’s SERP Retirement Benefits Deferral Period.

J. “Deferred Retirement Plan Benefit Commencement Date” shall mean a Retirement Plan Benefit Commencement Date that is later than a Participant’s Normal SERP Benefit Commencement Date.

K. “Deferred Retirement Plan Benefit Election Date” shall mean the date a Participant elects a Deferred Retirement Plan Benefit Commencement Date.

L. “Deferred SERP Benefit Commencement Date” shall mean with respect to a Part A Participant or Part B Participant, the date that is five (5) years after such Participant’s Normal SERP Benefit Commencement Date, or any existing Deferred SERP Benefit Commencement Date established under the Plan with respect to such Participant, as to which the Participant has made a Subsequent Election under the terms and provisions of the Plan.

M. “Deferred Supplemental Retirement Benefit Payment” shall mean the amount of any monthly Supplemental Retirement Benefit that is not paid to a Part B Participant for any month during such Part B Participant’s Supplemental Retirement Benefits Deferral Period.

N. “Disabled” shall mean that a Participant is unable to engage in substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or can be expected to last for a continuous period of not less than twelve (12) months, or is, by reason of any medically determinable physical or mental impairment which can be expected to last for a continuous period of not less than twelve (12) months, receiving income replacement benefits for a period of not less than three (3) months under an accident or health plan covering Employees of the Company.

O. “Effective Date” shall mean the effective date of the Plan, January 1, 2005.

P. “Election” shall mean the initial Election of a Participant to defer Deferred Compensation to the Participant for services performed for a Plan Year or other period pursuant to the Plan, which shall be on or before the expiration of thirty (30) days after the Initial Participation Date of such Participant.

Q. “Election Date” shall mean the date of the Election of a Part A Participant or Part B Participant that is made or deemed made pursuant to the terms of the Plan.

R. “Employee” shall mean any person who is in the regular full-time employment of the Company or is on authorized leave of absence therefrom, as

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determined by the personnel rules and practices of the Company. The term does not include persons who are retained by the Company solely as consultants or under contract.

S. “ERISA” shall mean the Employee Retirement Income Security Act of 1974, as amended.

T. “Excess Retirement Benefit” shall mean an amount equal the difference between (i) the Retirement Plan Benefit to which the Part A Participant would be entitled under the Retirement Plan if such Retirement Plan Benefit was computed without the restrictions or limitations imposed by Sections 401(a)(17) and 415(b) of the Code as now or hereafter in effect, less (ii) the amount of Retirement Plan Benefit payable to the Part A Participant under the Retirement Plan.

U. “Excess Retirement Benefit Catch-Up Payment” means a payment equal to the amount of each monthly Deferred Excess Retirement Benefit Payment, if any, to which a Part A Participant is entitled between the such Part A Participant’s Retirement Plan Benefit Commencement Date and his/her Deferred SERP Benefit Commencement Date.

V. “Final Average Earnings” shall mean the average of the highest thirty-six (36) consecutive months Compensation during the last sixty (60) month period of an Employee’s employment with the Company.

W. “Fixed Schedule” shall mean the distribution or payment of compensation deferred under the Plan in a fixed schedule of distributions or payments that are determined and fixed at the time the deferral of such Compensation is first elected by the Participant.

X. “Initial Participation Date” shall mean the date an Employee or Officer first becomes a Part A Participant and/or Part B Participant in the Plan.

Y. “Key Employee” shall mean an Employee who is (i) an officer of the Company having annual Compensation greater than $130,000 (adjusted for inflation at the same time and in the same manner as is provided for in Code Section 416(i) and limited to 50 Employees of the Company, (ii) a 5-percent owner of the Company, and (iii) a 1-percent owner of the Company having annual Compensation from the Company greater than $150,000.

Z. “Key Employee Catch-Up Payment” shall mean a lump sum payment equal to all regularly scheduled Excess Retirement Benefit and/or Supplemental Retirement Benefit monthly payments to which an Part A Participant or Part B Participant is entitled to under the Plan but which are not paid on and after the commencement of payment of his/her Retirement Plan Benefit because of a Key Employee Required Deferral Period.

AA. “Key Employee Required Deferral Period” shall mean the deferral of payment and distribution of an Excess Retirement Benefit or a Supplemental Retirement

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Benefit with respect to a Part A Participant or Part B Participant, respectively, until a date which is six (6) months after the date of the Separation from Service of such Participant.

BB. “Normal SERP Benefit Commencement Date” shall mean as to any Part A Participant or Part B Participant, the first day of the calendar month next following the date of occurrence of both (i) such Participant’s Separation from Service with the Company, and (ii) such Participant’s attainment of age fifty (50).

CC. “Officer” shall mean a person who is an elected officer of the Company.

DD. “Part A Participant” shall mean an Employee who is selected to participate in Part A of the Plan in accordance with the provisions of Article II of Part A of the Plan.

EE. “Part B Participant” shall mean an Employee who is selected and elects to participate in Part B of the Plan in accordance with the provisions of Article II of Part B of the Plan.

FF. “Performance-Based Compensation shall mean Compensation that is conditioned upon or subject to meeting certain requirements similar to those under Code Section 162(m), as more particularly provided for in Treasury Regulations issued under Code Section 409A.

GG. “Plan Agreement” shall mean a form of written agreement which is entered into by and between the Company and an Employee selected to become a Participant as a condition to participation in the Plan as provided in Sections 2.2 and 2.4 of Article II of Part B of the Plan.

HH. “Plan” shall mean this ONEOK, Inc. 2005 Supplemental Executive Retirement Plan as embodied herein and as amended from time to time.

II. “Prior Frozen SERP” shall mean the separate preexisting ONEOK, Inc. Supplemental Executive Retirement Plan, terminated and frozen by the Board of Directors effective December 31, 2004.

JJ. “Rabbi Trust” shall mean the trust created to hold assets which will be used to pay the benefits provided hereunder, as provided in Section 5.4 of Article V of this Part C of the Plan.

KK. “Retirement” and “Retire” shall mean termination of an Employee’s employment with the Company, other than termination of employment as a result of death of the Employee, irrespective of whether or not the Employee is considered to have retired under the Retirement Plan or for any other purpose at the time of his/her termination of employment with the Company.

LL. “Retirement Age” shall mean the retirement age of a Participant specified in the Participant’s Plan Agreement and the Plan.

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MM. “Retirement Plan” shall mean the Retirement Plan for Employees of ONEOK, Inc. and Subsidiaries.

NN. “Retirement Plan Benefit” shall mean the benefit or benefits to which a Part B Participant is entitled under the Retirement Plan.

OO. “Retirement Plan Benefit Commencement Date” means the date a Participant commences receiving payments of his/her Retirement Benefits under the Retirement Plan.

PP. “Separation from Service” shall mean the termination of a Participant’s employment with the Company.

QQ. “SERP Retirement Benefits Payments Deferral Period” means the period of time commencing on a Part A Participant’s or a Part B Participant’s Retirement Plan Benefit Commencement Date and ending on such Part B Participant’s Deferred SERP Benefit Commencement Date.

RR. “Service” shall mean employment of a Participant by the Company as a regular full-time employee.

SS. “Short-Term Incentive Cash Compensation” shall mean any payment by the Company under the ONEOK, Inc. Annual Employee Incentive Plan, the ONEOK, Inc. Annual Officer Incentive Plan, or any other incentive or commission plan established by the Company to pay employees additional cash compensation to reward performance, except that any payment by the Company under the ONEOK Energy Services Company, II Incentive Plan shall not be considered or treated as Short-Term Incentive Cash Compensation.

TT. “Specified Time” shall mean a specified date at which Deferred Compensation deferred by a Participant pursuant to the Plan is required to be distributed or paid and which is specified at the time the deferral of such Deferred Compensation is initially elected by the Participant.

UU. “Subsequent Election” shall mean an election made by a Participant with respect to the time or form of distribution of payment Deferred Compensation deferred under the Plan that is made at any time after his/her Election with respect to such Deferred Compensation.

VV. “Supplemental Retirement Benefit” shall mean the supplemental retirement benefit to be paid to a Part B Participant pursuant to Article III and other applicable provisions of Part B of the Plan.

WW. “Supplemental Retirement Benefit Catch-Up Payment” means a payment equal to the amount of each monthly Deferred Supplemental Retirement Benefit Payment, if any, to which a Part B Participant is entitled and which is not paid to such Part B Participant during the period between such Part B Participant’s Retirement Plan Benefit Commencement Date and his/her Deferred SERP Benefit Commencement Date.

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XX. “Totally and Permanently Disabled” means when, on the basis of medical evidence, it is determined that a Participant:

(a) is totally disabled so as to be prevented from any comparable employment with the Company, including a disability resulting from an occupational cause; and

(b) will be disabled permanently.

YY. “Unforeseeable Emergency” shall mean a sever financial hardship to the Participant resulting from illness or accident of the Participant, the Participant’s spouse, or a dependent (as defined in Code Section 152(a)) of the Participant, loss of the Participant’s property due to casualty, or other similar extraordinary circumstances arising as a result of events beyond the control of the Participant, and it is intended and directed with respect to any such Unforeseeable Emergency that any amounts distributed under the Plan by reason thereof shall not exceed the amounts necessary to satisfy such emergency plus amounts necessary to pay taxes reasonably anticipated as a result of the distribution, after taking into account the extent to which such hardship is or may be relieved through reimbursement or compensation by insurance or otherwise or by liquidation of the Participant’s assets (to the extent the liquidation of such assets would not itself cause severe financial hardship.

ZZ. “Years of Service” shall include each full year, but not any portion of a year, during which the Participant has been employed by the Company or any division or subsidiary thereof.

ARTICLE III

COMMITTEE

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The general administration of the Plan, including all provisions of Part A and Part B of the Plan, and any Plan Agreements executed hereunder, as well as construction and interpretation thereof, shall be vested in the Committee, the number and members of which shall be designated and appointed from time to time by, and shall serve at the pleasure of, the Board of Directors. Any such member of the Committee may resign by notice in writing filed with the Board of Directors. Vacancies shall be filled promptly by the Board of Directors.

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ARTICLE IV

ADOPTION OF PLAN BY SUBSIDIARY,

AFFILIATED OR ASSOCIATED COMPANIES

Any corporation which is a subsidiary of the Company may, with the approval of the Board of Directors, adopt the Plan and thereby come within the definition of Company in Article I of Part C of the Plan.

ARTICLE V

SOURCE OF BENEFITS

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a) At the Retirement of, and commencement of payment of an Excess Retirement Benefit or a Supplemental Retirement Benefit to a Plan Participant;

b) Upon a decision by the Committee, or by the Board of Directors; or

c) Upon a Change in Control.

Such funding may be in the form of single premium annuities, or an amount sufficient for the trustee to purchase single premium annuities, or life insurance policies or contracts insuring the lives of Participants, as the case may be, from qualified and financially sound insurance companies, and such other forms or types of investments the Company may select from time to time to provide the applicable vested Excess Retirement Benefits and Supplemental Retirement Benefits payable under the Plan and Plan Agreements. Such funding and the purchase of insurance, if any, will not relieve the Company of its obligations to pay or cause to be paid the benefits hereunder.

The Rabbi Trust may be maintained and administered to also provide for the funding of payment of amounts payable to participants in other deferred compensation and benefit plans of the Company. The funding, investments and administration of the Rabbi Trust in connection with such other separate plan or plans shall be separately administered and accounted for as determined to be necessary and appropriate by the Company and trustee pursuant to the terms of the Rabbi Trust. It shall be permissible for the trustee to invest funds of the Rabbi Trust in one or more forms of investment that is common to plans being funded thereunder.

The Rabbi Trust shall be a grantor trust of which the Company is the grantor within the meaning of the Code. The principal of the Rabbi Trust and any earnings thereon shall be

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held separate and apart from other funds of the Company and shall be used exclusively for the uses and purposes of Part A Participants and/or Part B Participants in the Plan and general creditors of the Company as specified hereinbelow and in the trust instrument. Part A Participants and Part B Participants in the Plan and their Beneficiaries shall have no preferred claim on, or any beneficial ownership in any assets of the Rabbi Trust; and any rights created under the Plan or any Plan Agreements, and the Rabbi Trust are to be made unsecured contractual rights of Part A Participants and Part B Participants (and their Beneficiaries, if applicable) against the Company; and assets held by the Rabbi Trust will be subject to the claims of the Company’s general creditors under federal and state law in the event of insolvency of the Company.

ARTICLE VI

TERMINATION OF EMPLOYMENT

Neither the Plan nor any Plan Agreement with a Participant hereunder, either singly or collectively, in any way obligate the Company, or any subsidiary of the Company, to continue the employment of a Part A Participant or a Part B Participant with the Company, or any subsidiary of the Company, nor does either limit the right of the Company or any subsidiary of the Company at any time and for any reason to terminate such Part A Participant’s or Part B Participant’s employment. Termination of a Part A Participant’s or Part B Participant’s employment with the Company, or any subsidiary of the Company, for any reason, whether by action of the Company, subsidiary, or such a Part A Participant or Part B Participant, shall immediately terminate such Participant’s participation in the Plan and any such Participant’s Plan Agreement, and all further obligations of either party thereunder, except as may be provided in Article VIII of this Part C, and the Participant’s Plan Agreement. In no event shall the Plan or a Plan Agreement, either singly or collectively, by their terms or implications constitute an employment contract of any nature whatsoever between the Company, or any subsidiary, and a Part A Participant or Part B Participant.

ARTICLE VII

TERMINATION OF PARTICIPATION

A Part A Participant and a Part B Participant reserves the right to terminate participation in the Plan and any such Participant’s Plan Agreement at any time by giving the Company written notice of such termination not less than 30 days (i) prior to the anniversary date of any contract or contracts of insurance on the life of such Part A Participant or Part B Participant which may be in force and utilized by the Company in connection with the Plan, or (ii) prior to the date a Part A Participant or Part B Participant selects for termination if no insurance contract is in effect.

ARTICLE VIII

TERMINATION, AMENDMENT, MODIFICATION,

OR SUPPLEMENT OF THE PLAN

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A. Notwithstanding anything to the contrary expressed or provided in the Plan or any Plan Agreement of a Part A Participant or Part B Participant, no amendment, modification or termination of the Plan, shall decrease a Part A Participant’s or Part B Participant’s accrued Excess Retirement Benefit or Supplemental Retirement Benefit, as applicable. For purposes of this Paragraph A., a Plan amendment which has the effect of decreasing a Part A Participant’s or Part B Participant’s accrued Excess Retirement Benefit or Supplemental Retirement Benefit, as the case may be, or eliminating any optional form of payment of a Participant’s accrued Excess Retirement Benefit or Supplemental Retirement Benefit, with respect to benefits attributable to service before the amendment shall be treated as reducing an accrued Excess Retirement Benefit or Supplemental Retirement Benefit. If a vesting schedule under the Plan or any Plan Agreement is amended, a Part A Participant’s and Part B Participant’s non-forfeitable percentage, determined as of the later of the date such amendment is adopted or the date it becomes effective, will not be less than the percentage computed under Part A and Part B of the Plan, as applicable, without regard to such amendment.

B. Except as provided in paragraph A of this Section 8.2, upon the termination of the Plan by the Board of Directors, or a termination of the Plan Agreement of a Participant, in accordance with the provisions for such termination, neither the Plan nor the Plan Agreement shall be of any further force or effect, and no party shall have any further obligation under either the Plan or any Plan Agreement so terminated, except as provided in the Plan or Plan Agreement with respect to accrued benefits at the time of such termination or as elsewhere provided in the Plan.

C. For purposes of paragraphs A and B of this Section 8.2, the term “Plan” shall also mean and include any substituted plan that may be established in event of a Change of Control as described in Section 8.1, above, and the terms “Excess Retirement

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ARTICLE IX

TREATMENT OF BENEFITS

The Excess Retirement Benefit provided for a Part A Participant and the Supplemental Retirement Benefit provided for a Part B Participant under the Plan and/or under any Plan Agreement are in addition to any other benefits available to such Participant under any other Plan, plan or agreement of the Company for its Employees and the Participants, and, except as may be otherwise expressly provided for, the Plan and Plan Agreements entered into hereunder shall supplement and shall not supersede, modify, or amend any other Plan, plan or agreement of the Company. The Excess Retirement Benefits and Supplemental Retirement Benefits under the Plan and/or Plan Agreements entered into hereunder shall not be considered compensation for the purpose of computing contributions or benefits under any plan maintained by the Company, or any of its subsidiaries, which is qualified under Section 401(a) of the Code.

ARTICLE X

RESTRICTIONS ON ALIENATION OF BENEFITS

No Excess Retirement Benefit or Supplemental Retirement Benefit under the Plan or a Plan Agreement shall be subject to anticipation, alienation, sale, assignment, pledge, encumbrance, or charge, and any attempt to anticipate, alienate, sell, assign, pledge, encumber, or charge the same shall be void. No Excess Retirement Benefit Supplemental Retirement Benefit under the Plan or under any Plan Agreement shall in any manner be liable for or subject to the debts, contracts, liabilities, or torts of the person entitled to such thereto. If any Part A Participant or Part B Participant under the Plan or a Plan Agreement should become bankrupt or attempt to anticipate, alienate, sell, assign, pledge, encumber, or charge any right to a benefit under the Plan or under any Plan Agreement, then such right or benefit shall, in the discretion of the Committee, cease, and in such event, the Committee may, but shall have no duty to hold or apply the same or any part thereof for the benefit of such Part A Participant or Part B Participant, or his/her Beneficiary, in such portion as the Committee, in its sole and absolute discretion, may deem proper.

ARTICLE XI

MISCELLANEOUS

The following requirements stated in this Section 11.1 shall apply to the Plan, to all Elections or Subsequent Elections made by Participants under the Plan, and to all distributions and payments made pursuant to the Plan.

A. Any Compensation deferred under the Plan shall not be distributed earlier than

(a) Separation from Service of the Participant,

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(b) the date the Participant becomes Disabled,

(c) death of the Participant,

(d) a Specified Time (or pursuant to a Fixed Schedule) specified under the Plan at the date of deferral of such Compensation,

(e) a Change in Ownership or Control, or

(f) the occurrence of an Unforeseeable Emergency.

B. Notwithstanding the foregoing, in the case of a Participant who is a Key Employee, no distribution shall be made before the date which is six (6) months after the date of the Participant’s Separation from Service, or, if earlier, the date of death of such Participant.

C. No acceleration of the time or schedule of any distribution or payment under the Plan shall be permitted or allowed, except to the extent provided in Treasury Regulations issued under Code Section 409A.

If the Plan, or the Committee acting pursuant to the Plan, permits under any Subsequent Election by a Participant a delay in a payment or a change in the form of payment of Compensation deferred under the Plan, such Subsequent Election shall not take effect until at least twelve (12) months after the date on which it is made. In the case of a Subsequent Election related to a payment to be made upon Separation from Service of a Participant, at a Specified Time or pursuant to a Fixed Schedule, or upon a Change in Ownership or Control, the first payment with respect to which such Subsequent Election is made shall be deferred for a period of not less than five (5) years from the date such payment would otherwise have been made; and any such Subsequent Election related to a payment at a Specified Time or pursuant to a Fixed Schedule may not be made less than twelve (12) months prior to the date of the first scheduled payment to which it relates.

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Exhibit 10.3

ONEOK, Inc.

EMPLOYEE NONQUALIFIED

DEFERRED COMPENSATION PLAN

Amended and Restated Effective December 16, 2004

ONEOK, Inc.

EMPLOYEE NONQUALIFIED DEFERRED COMPENSATION PLAN

Table of Contents

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ONEOK, Inc.

EMPLOYEE NONQUALIFIED DEFERRED COMPENSATION PLAN

ARTICLE I - PURPOSE

This ONEOK, Inc. Employee Nonqualified Deferred Compensation Plan (the “Plan”) and related agreements between the Employer and certain management or highly compensated employees is an unfunded, nonqualified deferred compensation plan and arrangement. The purpose of the Plan is to provide a select group of management and highly compensated employees of the Employer with the option to defer the receipt of portions of their compensation payable for services rendered to the Employer, and provide nonqualified deferred compensation benefits which are not available to such employees by reason of limitations on employer and employee contributions to qualified pension or profit-sharing plans under the federal tax laws.

It is intended that the Plan will assist in attracting and retaining qualified individuals to serve as officers and managers of the Employer; and the Plan is intended to constitute a plan which is unfunded and maintained by an employer primarily for the purpose of providing deferred compensation for a select group of management or highly compensated employees within the meaning of, and as described in Section 201(2) and related provisions of ERISA.

The Plan is generally effective on May 15, 1997, but shall first apply to the deferral of Compensation by Participants thereunder beginning on June 1, 1997. The Plan was amended and restated November 1, 1999, October 19, 2000 and February 15, 2001, and December 16, 2004.

ARTICLE II - DEFINITIONS

When used in this Plan and initially capitalized, the following words and phrases shall have the meanings indicated:

“Account” means the sum of a Participant’s Deferral Account and Matching Account under the Plan.

“Base Salary” means a Participant’s basic wage or salary paid by an Employer to the Participant without regard to any increases or decreases in such basic wage or salary as a result of (i) an election to defer basic wage or salary under this Plan or (ii) an election between benefits or cash provided under a plan of an Employer maintained pursuant to Sections 125 or 401(k) of the Code, and as limited in Exhibit B attached hereto. The Base Salary does not include any Lump

Sum Merit Award paid to a Participant, nor any Bonus, as defined in Section 2.5, below.

“Beneficiary” means the person or persons designated or deemed to be designated by the Participant pursuant to Article VII to receive benefits payable under the Plan in the event of the Participant’s death.

“Board” means the Board of Directors of the Corporation.

“Bonus” means the cash bonus paid by the Employer to a Participant under the Key Employee Incentive Plan without regard to any decreases as a result of (i) an election to defer all or any portion of such Bonus under this Plan or (ii) an election between benefits or cash provided under the Thrift Plan or any other plan of the Employer maintained pursuant to Section 401(k) of the Code.

A “Change in Control” shall mean the occurrence of any of the following:

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