FUEL TECH, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE

SECURITIES EXCHANGE ACT OF 1934

Check the appropriate box:

FUEL TECH, INC.

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

April 21, 2025

Dear Fellow Stockholders,

This year’s Annual Meeting of Stockholders of Fuel Tech, Inc. will be held at 10:00 a.m., Central Time, on Thursday, June 5, 2025 at the offices of Fuel Tech, Inc., 27601 Bella Vista Parkway, Warrenville, Illinois 60555.

Whether or not you expect to attend in person, the return of the enclosed proxy card as soon as possible or the submission of a proxy by telephone or the Internet by following the instructions on the proxy card will ensure that your shares will be represented at the Annual Meeting. If you do attend the Annual Meeting, you may withdraw your previously submitted proxy should you wish to vote in person.

On behalf of the Board of Directors and management of Fuel Tech, Inc., I would like to thank you for your continued support and confidence.

Sincerely,

Vincent J. Arnone

Chairman and CEO

Fuel Tech, Inc.

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD JUNE 5, 2025

To the Stockholders of Fuel Tech, Inc.:

The annual meeting of stockholders of Fuel Tech, Inc., a Delaware corporation (Fuel Tech), will be held Thursday, June 5, 2025, at 10:00 a.m. local time at the offices of Fuel Tech, Inc., 27601 Bella Vista Parkway, Warrenville, Illinois 60555 (Annual Meeting), to consider and vote on the following items, each of which is explained in the attached proxy statement (Proxy Statement):

Only holders of Fuel Tech’s common stock of record as of the close of business on April 8, 2025 are entitled to vote at the Annual Meeting. We ask that you promptly sign, date and mail the enclosed proxy card in the return envelope provided or submit a proxy by telephone or the Internet by following the instructions on the proxy card. Stockholders who attend the Annual Meeting may revoke their previously submitted proxy and vote in person.

By Order of the Board of Directors,

Bradley W. Johnson

Vice President, General Counsel and Secretary

MAKE YOUR VOTE COUNT

Please vote your shares promptly. Voting your shares now via the internet, by telephone, or by signing, dating, and returning the enclosed proxy card or voting instruction form will save us the expense of additional solicitation. Submitting your proxy now will not prevent you from voting your shares during the annual meeting, as your proxy is revocable at your option.** Fuel Tech**’s Proxy Statement and Annual Report to Stockholders are available at:www.envisionreports.com/FTEK.

Note About Forward-Looking Statements

This Proxy Statement includes estimates, projections, statements relating to our business plans, objectives, and expected operating results that are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements generally are identified by the words “believe,” “project,” “expect,” “anticipate,” “estimate,” “intend,” “strategy,” “future,” “opportunity,” “plan,” “may,” “should,” “will,” “would,” “will be,” “will continue,” “will likely result,” and similar expressions. For us, particular uncertainties that could cause our actual results to be materially different than those expressed in our forward-looking statements include:

These or other uncertainties may cause our actual future results to be materially different than those expressed in our forward-looking statements. We do not undertake to update our forward-looking statements.

Questions and Answers About the Proxy Statement and

Our 2025 Annual Meeting

Why am I receiving these materials?

This proxy statement is furnished in connection with the solicitation of proxies by the Board of Directors of Fuel Tech, Inc. (theCompany,Fuel Tech,we,us andour) for use at our Annual Meeting of Stockholders on June 5, 2025 at 10:00 a.m., local time, and any adjournments or postponements thereof (theAnnual Meeting).

Why do the proxy materials contain information regarding the Internet availability of proxy materials?

Pursuant to rules adopted by the Securities and Exchange Commission (SEC), we have opted to provide access to our proxy materials primarily over the Internet, which will allow us to capture costs and reduce the environmental impact of printing and mailing proxy materials. Proxy materials for the Annual Meeting, including our Annual Report on Form 10-K for the year ended December 31, 2024 and this proxy statement, are available over the Internet by accessing www.envisionreports.com/FTEK or at the “Investors” tab of website atwww.FTEK.com. Instructions on how to access the proxy materials over the Internet or to request an additional printed copy are available atwww.envisionreports.com/FTEK. You also can obtain a printed copy of this proxy statement, free of charge, by writing to: General Counsel, c/o Fuel Tech, Inc., 27601 Bella Vista Parkway, Warrenville, Illinois 60555, or by submitting a request via email to proxy@ftek.com or by telephone at 630-845-4500.

Who is paying for this proxy solicitation?

We are responsible for the expense of soliciting proxies, including the cost of preparing, assembling and mailing the notice, proxy statement and proxy. We may pay persons holding our common stock (Common Stock) for expenses incurred in sending proxy materials to their principals. In addition to solicitation of proxies by mail, our directors, officers and employees, without additional compensation, may solicit proxies by telephone, electronically via e-mail and personal interview. We may also retain a proxy solicitation firm to assist in the solicitation of proxies.

What voting rights do I have as a Stockholder?

On each matter to be voted on, you have one vote for each outstanding share of our Common Stock you own as of April 8, 2025, the record date for the Annual Meeting. Only stockholders of record at the close of business on April 8, 2025 are entitled to receive notice of and to vote at the Annual Meeting. On this record date, there were 30,769,258 shares of Common Stock outstanding and entitled to vote. Stockholders do not have the right to vote cumulatively in the election of directors.

How do I vote?

If you are a stockholder of record, you can vote:

Proxies submitted via the telephone or Internet must be received by 11:00 p.m. Central Time on June 4, 2025. More detailed instructions are included on the proxy card. In order to submit a proxy via the telephone or Internet, please follow the instructions on the proxy card.

If you are a stockholder of record, the proxy holders will vote your shares based on your directions. If you sign and return your proxy card, but do not properly direct how your shares of Common Stock should be voted, the proxy holders will vote “FOR” the director nominees, “FOR” the ratification of RSM US LLP, and “FOR” the approval, on an advisory basis, of Fuel Tech’s executive compensation. The proxy holders will use their discretion on any other proposals and other matters that may be brought before the Annual Meeting.

If you hold shares of Common Stock through a broker or nominee, you may vote in person at the Annual Meetingonly if you have obtained a signed proxy from your broker or nominee giving you the right to vote your shares.

Can I revoke or change my vote after I submit a proxy?

Yes. You can revoke your proxy or change your vote at any time before the proxy is voted at the Annual Meeting. This can be done by either submitting another properly completed proxy card with a later date, sending a written notice to our Secretary (we must receive your new proxy card or written notice before the Annual Meeting begins), or you may attend the Annual Meeting and vote in person. You should be aware that simply attending the Annual Meeting will not automatically revoke your previously submitted proxy. Instead, you must notify a Fuel Tech representative at the Annual Meeting of your desire to revoke your proxy and vote in person.

What vote is required to approve each of the proposals?

What constitutes a quorum?

A quorum of stockholders will be present at the Annual Meeting if at least one-third of the aggregate voting power of Common Stock outstanding on the record date is represented at the Annual Meeting, in person or by proxy. With 30,769,258 shares outstanding as of the close of business on the record date, stockholders representing at least 10,153,855 shares will be required to establish a quorum. Abstentions and broker non-votes will be counted towards the quorum requirement.

Can Stockholders make proposals for the 2025 Annual Meeting?

Stockholders may present proposals that may be proper subjects for inclusion in the proxy statement and for consideration at an Annual Meeting. To be included in the proxy statement for this year’s Annual Meeting, Fuel Tech must have received such proposals no later than December 16, 2024.

Pursuant to our By-Laws, stockholders may present proposals that are proper subjects for consideration at an annual meeting. The By-Laws require all stockholders who intend to make proposals at an annual meeting to submit their proposals to Fuel Tech within specific dates in order to be eligible for consideration at an annual meeting. SeeStockholder Communications with the Board on page 33, andStockholder Proposals for 2025 Annual Meeting on page 33 for more information. To be eligible for consideration at the 2025 Annual Meeting, proposals that were not submitted for inclusion in the proxy statement by December 12, 2024 must have been received no earlier than February 16, 2025 and no later than March 14, 2025. We did not receive any stockholder proposals for the 2025 Annual Meeting.