As filed with the Securities and Exchange Commission on August 18, 2025 Registration No. 333-[●] UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ADVENT TECHNOLOGIES HOLDINGS, INC. (Exact name of registrant as specified in its charter) 5637 La Ribera St. Suite A, Livermore, CA 94550 (925) 455-9400 (Address, including zip code, and telephone number, including area code, of registrant's principal executive offices) Gary He ...