UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): ~~November~~May 514, ~~2025~~2026

Advent Technologies Holdings, Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-38742

83-0982969

(State or other jurisdiction

of incorporation)

(Commission
File Number)

(IRS Employer

Identification No.)

5637 La Ribera Street

Suite A

Livermore, CA 94550

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (925) 455-9400

Check the appropriate box below if the Form 8−K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a−12 under the Exchange Act (17 CFR 240.14a−12)

☐	Pre−commencement communications pursuant to Rule 14d−2(b) under the Exchange Act (17 CFR 240.14d−2(b))

☐	Pre−commencement communications pursuant to Rule 13e−4(c) under the Exchange Act (17 CFR 240.13e− 4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol	Name of each exchange on which registered
Common stock, par value $0.0001 per share	ADN	Over The Counter (OTC) Market
Warrants to purchase one share of common stock, each at an exercise price of $345.00	ADNWW	Over The Counter (OTC) Market

Title of each class		Trading Symbol		Name of each exchange on which registered
N/A		N/A		N/A

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 18.0201 ~~Termination~~Other ~~of a Material Definitive Agreement~~Events.

~~As previously disclosed in a Current Report on~~On ~~Form~~May ~~8-K~~14, ~~filed~~2026, ~~with~~Advanced ~~the~~Energy ~~Securities~~Technologies ~~and~~Single ~~Exchange~~Member ~~Commission on August 7~~SA, ~~2025,~~a onwholly-owned ~~August~~subsidiary 1,of ~~2025,~~ Advent Technologies Holdings, Inc. (the “Company”), received ~~entered into~~ a ~~Securities~~letter ~~Purchase~~from ~~Agreement (~~the ~~“Securities~~Secretariat ~~Purchase~~General ~~Agreement”)~~for ~~with Hudson Global Ventures LLC (“Hudson”)~~Industry, ~~pursuant~~Directorate toGeneral ~~which~~for ~~Hudson~~Industrial ~~made~~Policy a& ~~loan~~Reforms toand the ~~Company, evidenced by a Convertible Promissory Note in~~Directorate ~~the~~for ~~aggregate~~Industrial ~~principal~~Policy ~~amount~~ of ~~$235,000.00,~~the ~~including~~Hellenic anRepublic ~~original~~Ministry ~~issue discount~~ of ~~$25,000.00~~Development (notifying the ~~“Promissory~~Company ~~Note”), with~~that ~~interest~~Project ~~accruing~~EL02 atGreen anHIPo ~~annual~~has ~~rate~~been ofwithdrawn from ~~twelve percent (12%) to be computed on~~ the ~~basis~~Hydrogen ofIPCEI aHy2 ~~360-day~~Tech ~~year,~~wave inprogram ~~addition~~due to a ~~pre-funded warrant~~failure to ~~purchase~~meet ~~130,000~~certain ~~shares~~internal ~~of the Company’s common stock, par value $0~~requirements.~~0001 per share.~~

As of November 5, 2025, the Company repaid all amounts owed pursuant to the Promissory Note and satisfied all conditions of the Promissory Note; as a result of such satisfaction, the Promissory Note is satisfied in full and terminated upon repayment and satisfaction.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: ~~November~~May 1015, ~~2025~~2026

	Advent Technologies Holdings, Inc.

	By:	/s/ Gary Herman
	Name:	Gary Herman
	Title:	Chief Executive Officer

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