Birchtech Corp.

As filed with the Securities and Exchange Commission on January 13, 2026.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM****S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

BIRCHTECH CORP.

(Exact name of registrant as specified in its charter)

1810 Jester Drive

Corsicana, Texas 75109

(614) 505-6115

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Richard MacPherson

President, Chief Executive Officer and Secretary

1810 Jester Drive

Corsicana, Texas 75109

(614) 505-6115

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of all communications, including communications sent to agent for service, should be sent to:

Approximate date of commencement of proposed sale to the public:As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box:☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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 7(a)(2)(B) of the Securities Act.☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until this registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted

BIRCHTECH CORP.

4,819,278 Shares

Common Stock

Birchtech Corp. (the “Company”, “we”, “us” or “our”) is offering 4,819,278 shares of our common stock, par value $0.001 per share (the “common stock”), based on an assumed public offering price of $4.15, which was the last reported sale price of our common stock on the OTCQB (as defined below) on January 9, 2026.

Our common stock is presently traded on the Toronto Stock Exchange (“TSX”) under the symbol “BCHT”, and is quoted on the OTCQB market tier operated by OTC Markets Group Inc. (“OTCQB”) under the symbol “BCHTD”. On January 9, 2026, the last reported sale price of our common stock on the OTCQB was $4.15 per share. The final public offering price of the shares of common stock sold in this offering will be determined through negotiation between us and the underwriters in the offering and the assumed public offering price of our common stock used throughout this prospectus may not be indicative of the final public offering price. The share and per share information in the prospectus, unless otherwise noted, reflect the reverse stock split of our outstanding shares of common stock at a 1-for-5 ratio, which became effective December 26, 2025.

In connection with this offering, we intend to apply to list the common stock on the New York Stock Exchange American Exchange (the “NYSE American”) under the symbol “BCHT”. The approval of the listing of the common stock on the NYSE American is a condition to the completion of this offering and we expect that, if approved, the common stock will begin trading on the NYSE American on or around the date of this prospectus, at which point the common stock will cease to be traded on the OTCQB. No assurance can be given that our application will be approved or, if we receive approval, that a trading market will develop or, if developed, that it will be sustained or that the trading prices of the common stock on the OTCQB and TSX will be indicative of the prices of our common stock if traded on the NYSE American. We cannot assure you that our common stock will become eligible for trading on the NYSE American or on any other exchange or market.

We are a “smaller reporting company” as such term is defined under federal securities laws, and, as such, have elected to take advantage of certain reduced public company reporting requirements.

Investing in our common stock involves a high degree of risk. Before buying any shares, you should carefully read the discussion of the material risks of investing in our common stock that are described in “Risk Factors” beginning on page11** of this prospectus.**

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

We have granted the underwriters a 30-day option to purchase up to an additional 722,892 shares of common stock, or 15% of the total number of shares of common stock sold in this offering, solely to cover over-allotments, if any. If the underwriters exercise the option in full, the total underwriting discounts and commissions, based upon the assumed public offering price of $4.15 per share, payable by us will be $1,607,229, and the total proceeds to us, before expenses, will be $21,392,776.

We expect to deliver the shares of common stock on or about , 2026.

The date of this prospectus is , 2026.