Birchtech Corp.

Item 5.02(c) - Appointment of Chief Financial Officer and Chief Operating Officer Effective May 1, 2026, the Company appointed Michael Mioska as its Chief Financial Officer. Michael Mioska, age 45, is a Chartered Professional Accountant with over 20 years of accounting, audit and financial reporting experience in a variety of industries, in both the United States and Canada. Prior to his appointment, Mr. Mioska was employed by DeNovo Group providing finance, financial reporting and M&A advisory-related services to a range of public companies as an independent consultant since 2021, including Birchtech Corp. since 2023. From 2005 to 2021, Mr. Mioska worked at a public accounting firm in Vancouver, BC providing similar finance services. Mr. Mioska earned a Bachelor of Arts from the University of British Columbia and a Masters of Business Administration from Laurentian University. He is a Chartered Professional Accountant (CPA) in Canada. Mr. Mioska does not have any family relationships with any of the Company’s directors or executive officers, or any person nominated or chosen by the Company to become a director or executive officer. Except as otherwise disclosed herein, there are no arrangements or understandings in connection with Mr. Mioska’s appointment, and there are no related party transactions between the Company and Mr. Mioska that would require disclosure under Item 404(a) of Regulation S-K. The terms of Mr. Mioska’s compensation have not yet been finalized. The Company expects to enter into an arrangement with a third-party employer of record pursuant to which Mr. Mioska will be employed by such third party and assigned to provide services to the Company. The Company expects to finalize these arrangements in the near term and will disclose the material terms thereof upon finalization. The Company will also enter into a standard indemnification agreement with Mr. Mioska, the form of which has been filed with the Securities and Exchange Commission. A copy of the Company’s press release announcing the appointment of Mr. Mioska is filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. In addition, on May 1, 2026, the Company appointed James Trettel as its Chief Operating Officer, and in connection with his appointment, he ceased serving as Executive Vice President of Operations. Mr. Trettel’s biographical information is set forth in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 filed on March 31, 2026, which is incorporated herein by reference. See Item 5.02(e) below for information on the amended and restated employment agreement entered into with Mr. Trettel.