U.S. SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the month of September 2017

Commission File Number: 001-36885

TANTECH HOLDINGS LTD

Tantech Holdings Ltd

c/o Zhejiang Tantech Bamboo Technology Co., Ltd

No. 10 Chen Shan Road, Shuige Industrial Zone

Lishui City, Zhejiang Province 323600

+86-578-226-2305

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F   x             Form 40-F   ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ¨

Explanatory Note:

As previously announced, on February 9, 2017, Tantech Holdings Ltd (the “Registrant”) entered into a Convertible Note Agreement with ARC Capital Ltd. to secure a loan for $2,000,000. On September 27, 2017, the parties mutually agreed to terminate the Convertible Note Agreement, effective immediately. From the date the parties entered into the Convertible Note Agreement through the dated of termination, no funds were advanced under the Convertible Note Agreement, and no amounts were due.