融合燃料绿色PLC-A美股招股说明书(2025-07-28版)

This prospectus supplement amends and supplements the information in the prospectus supplement, dated May 16, 2025 (the “Prior Prospectus Supplement”), and the prospectus, dated May 13, 2022 (the “Prospectus”), of Fusion Fuel Green PLC, an Irish publiclimited company (“we,” “us,” “our,” or the “Company”), relating to the offer and sale of up to $2,064,262 of Class A ordinary shareswith a nominal value of $0.0035 each of the Company (“Class A Ordinary Shares”), pursuant to the At The Market Offering Agreement between the Company and H.C. Wainwright & Co., LLC (“Wainwright”), dated as of May 16, 2025 (the “ATMAgreement”). This prospectus supplement is registering the offer and sale of up to $4,184,136 of our Class A Ordinary Shares, not including the Class A Ordinary Shares previously sold pursuant to the ATM Agreement. This prospectus supplement should be read inconjunction with the Prior Prospectus Supplement, and is qualified by reference thereto, except to the extent that the informationherein amends or supersedes the information contained in the Prior Prospectus Supplement. This prospectus supplement is notcomplete without, and may only be delivered or utilized in connection with, the Prior Prospectus Supplement and any futureamendments or supplements thereto.Our Class A Ordinary Shares and our public warrants are listed on The Nasdaq Capital Market tier of The Nasdaq Stock Market LLCunder the symbols “HTOO” and “HTOOW”, respectively. The last reported sale price of the Class A Ordinary Shares and the publicwarrants on July 25, 2025 was $6.99 per share and $0.04 per warrant, respectively. in any12-monthperiod so long as our public float remains below $75.0million. In the event that subsequent to the date of thisprospectus supplement the aggregate market value of our outstanding Class A Ordinary Shares held by non-affiliates equals or exceeds$75,000,000, such one-third limitation on sales shall not apply to sales subsequently made pursuant to this prospectus supplement. of Form F-3 during the 12-calendar month period that ends on and includes the date hereof, and therefore $4,184,136 is available to besold pursuant to this prospectus supplement.Investing in our securities is highly speculative and involves a high degree of risk.See “Risk Factors” beginning on page S-5 ofthe Prior Prospectus Supplement and as described in or in exhibits to certain of the documents we may incorporate byreference therein, for a discussion of information that should be considered in connection with an investment in our securities. H.C. Wainwright & Co.