# EDGAR Filing Document

**Accession Number:** 0002019804
**File Stem:** 0001104659-26-000287
**Filing Date:** 2026-1
**Character Count:** 65900
**Document Hash:** 1e319e07ad8aac0aa52e9a3e0fbd2e94
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-000287.hdr.sgml**: 20260105

**ACCESSION NUMBER**: 0001104659-26-000287

**CONFORMED SUBMISSION TYPE**: S-8

**PUBLIC DOCUMENT COUNT**: 18

**FILED AS OF DATE**: 20260105

**DATE AS OF CHANGE**: 20260105

**EFFECTIVENESS DATE**: 20260105

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Terrestrial Energy Inc. /DE/
- **CENTRAL INDEX KEY:** 0002019804
- **STANDARD INDUSTRIAL CLASSIFICATION:** FABRICATED PLATE WORK (BOILER SHOPS) [3443]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 981785406
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-8
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-292571
- **FILM NUMBER:** 26504353

**BUSINESS ADDRESS:**
- **STREET 1:** 2730 W. TYVOLA ROAD, SUITE 100
- **CITY:** CHARLOTTE
- **STATE:** NC
- **ZIP:** 28217
- **BUSINESS PHONE:** 203-930-2200

**MAIL ADDRESS:**
- **STREET 1:** 2730 W. TYVOLA ROAD, SUITE 100
- **CITY:** CHARLOTTE
- **STATE:** NC
- **ZIP:** 28217

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** HCM II Acquisition Corp.
- **DATE OF NAME CHANGE:** 20240415

**As filed with the United States Securities and Exchange Commission on January 2, 2026**

**Registration No. 333-**

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**FORM S-8**

**REGISTRATION STATEMENT**

**UNDER**

**THE SECURITIES ACT OF 1933**

**TERRESTRIAL ENERGY INC.**

(Exact name of registrant as specified in its charter)

---

| | |
|:---|:---|
| **Delaware** | **98-1785406** |
| (State or other jurisdiction of<br> incorporation or organization) | (I.R.S. Employer<br> Identification No.) |
| **2730 W. Tyvola Road, Suite 10,<br> Charlotte, NC** | **28217** |
| (Address of Principal Executive Offices) | (Zip Code) |

---

**Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan**

**Terrestrial Energy Inc. 2025 Equity Incentive Plan**

(Full title of the plan)

**Steven Millsap<br> General Counsel, Secretary and Chief Compliance Officer<br> 2730 W. Tyvola Road, Suite 10,<br> Charlotte, NC 28217**

(Name and address of agent for service)

**(646) 687-8212**

(Telephone number, including area code, of agent for service)

**Copies to:**

Eliot Robinson

Tyler Mark

Bryan Cave Leighton Paisner LLP

One Atlantic Center, 14th Floor,

1201 W. Peachtree St., N.W.,

Atlanta, GA 30309-3471

(404) 572-6600

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.

Large accelerated filer ¨ Accelerated filer ◻ <br> Non-accelerated filer x Smaller reporting company ⌧ <br> Emerging growth company x

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. ◻

**EXPLANATORY NOTE**

Terrestrial Energy Inc. (the "Company" or the "Registrant") has filed with the Securities and Exchange Commission (the "Commission") this registration statement on Form S-8 (this "Registration Statement") to register under the Securities Act of 1933, as amended (the "Securities Act") (i) 18,678,584 shares of Common Stock, par value $0.0001 per share (the "Common Shares") underlying options that were issued under the Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan (the "Legacy Plan") assumed by the Company pursuant to that certain Business Combination Agreement, dated as of March 26, 2025, and (ii) 15,473,715 Commons shares reserved for issuance pursuant to the Terrestrial Energy Inc. 2025 Equity Incentive Plan (the "2025 Plan").

**PART I**

**INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS**

**Item 1. Plan Information.\***

**Item 2. Registrant Information and Employee Plan Annual Information.\***

\* As permitted by Rule 428 under the Securities Act, this Registration Statement omits the information specified in Part I of Form S-8. The documents containing the information specified in Part I of this Registration Statement will be sent or given to each participant in the Legacy Plan and the 2025 Plan, as applicable, in accordance with Rule 428(b)(1). Such documents are not required to be and are not being filed with the Commission, either as part of this Registration Statement or as prospectuses or prospectus supplements pursuant to Rule 424 under the Securities Act. These documents and the documents incorporated by reference in this Registration Statement pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the Securities Act.

**PART II**

**INFORMATION REQUIRED IN THE REGISTRATION STATEMENT**

**Item 3. Incorporation of Documents by Reference.**

The Company hereby incorporates by reference in this Registration Statement the following:

● the prospectus dated [December 30, 2025](https://www.sec.gov/Archives/edgar/data/2019804/000110465925125280/tmb-20250930x424b3.htm) , filed by the Company pursuant to Rule <u>424(b)</u> under the Securities Act relating to the registration statement on <u>Form S-1</u> originally filed on November 26, 2025, as amended ([File No. 333- 291796](https://www.sec.gov/ix?doc=/Archives/edgar/data/2019804/000110465925116127/tmb-20250930xs1.htm)) (the "424(b) Prospectus");

● the Company's Current Reports on Form 8-K (or amended Current Reports on Form 8-K/A, as applicable) filed with the SEC on [November 3, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/2019804/000121390025105304/ea0263386-8k_terres.htm) , [November 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/2019804/000110465925112689/tm2531081d1_8ka.htm) and [November 24, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/2019804/000110465925115406/tm2531980d1_8k.htm) ;

● the description of the Company's securities contained in the section titled "Description of Capital Stock" of the Company's 424(b) Prospectus and any other amendment or report filed for the purpose of updating such description.

All documents subsequently filed by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), prior to the filing of a post-effective amendment which indicates that all securities offered hereby have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be a part hereof from the date of filing of such documents. Any statement contained herein or in a document, all or a portion of which is incorporated or deemed to be incorporated by reference herein, shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

Notwithstanding the foregoing, no information is incorporated by reference in this Registration Statement where such information under applicable forms and regulations of the Commission is not deemed to be "filed" under Section 18 of the Exchange Act or otherwise subject to the liabilities of that section, unless the report or filing containing such information indicates that the information therein is to be considered "filed" under the Exchange Act or is to be incorporated by reference in this Registration Statement.

**Item 4. Description of Securities.**

Not applicable.

**Item 5. Interests of Named Experts and Counsel.**

Not applicable.

**Item 6. Indemnification of Directors and Officers.**

Subsection (a) of Section 145 of the DGCL empowers a corporation to indemnify any person who was or is a party or who is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with such action, suit or proceeding if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable cause to believe the person's conduct was unlawful.

Subsection (b) of Section 145 empowers a corporation to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor by reason of the fact that the person acted in any of the capacities set forth above, against expenses (including attorneys' fees) actually and reasonably incurred by the person in connection with the defense or settlement of such action or suit if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or the court in which such action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem proper.

Section 145 further provides that to the extent a director or officer of a corporation has been successful on the merits or otherwise in the defense of any action, suit or proceeding referred to in subsections (a) and (b) of Section 145, or in defense of any claim, issue or matter therein, such person shall be indemnified against expenses (including attorneys' fees) actually and reasonably incurred by such person in connection therewith; that indemnification provided for by Section 145 shall not be deemed exclusive of any other rights to which the indemnified party may be entitled; and the indemnification provided for by Section 145 shall, unless otherwise provided when authorized or ratified, continue as to a person who has ceased to be a director, officer, employee or agent and shall inure to the benefit of such person's heirs, executors and administrators. Section 145 also empowers the corporation to purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against any liability asserted against such person and incurred by such person in any such capacity, or arising out of his status as such, whether or not the corporation would have the power to indemnify such person against such liabilities under Section 145.

Section 102(b)(7) of the DGCL provides that a corporation's certificate of incorporation may contain a provision eliminating or limiting the personal liability of a director or officer to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director or officer, provided that such provision shall not eliminate or limit the liability (i) for any breach of the director's or officer's duty of loyalty to the corporation or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL, or (iv) for any transaction from which the director or officer derived an improper personal benefit.

Additionally, our Certificate of Incorporation limits the liability of our directors to the fullest extent permitted by the DGCL, and our Bylaws provide that we will indemnify them to the fullest extent permitted by such law. We have entered into and expect to continue to enter into agreements to indemnify our directors, executive officers and other employees as determined by our board of directors. Under the terms of such indemnification agreements, we are required to indemnify each of our directors and officers, to the fullest extent permitted by the laws of the state of Delaware, if the basis of the indemnitee's involvement was by reason of the fact that the indemnitee is or was our director or officer or was serving at our request in an official capacity for another entity. We must indemnify our officers and directors against all reasonable fees, expenses, charges and other costs of any type or nature whatsoever, including any and all expenses and obligations paid or incurred in connection with investigating, defending, being a witness in, participating in (including on appeal), or preparing to defend, be a witness or participate in any completed, actual, pending or threatened action, suit, claim or proceeding, whether civil, criminal, administrative or investigative, or establishing or enforcing a right to indemnification under the indemnification agreement. The indemnification agreements also require us, if so requested, to advance all reasonable fees, expenses, charges and other costs that such director or officer incurred, provided that such person will return any such advance if it is ultimately determined that such person is not entitled to indemnification by us. Any claims for indemnification by our directors and officers may reduce our available funds to satisfy successful third-party claims against us and may reduce the amount of money available to us.

**Item 7. Exemption from Registration Claimed.**

Not applicable.

**Item 8. Exhibits.**

---

| | |
|:---|:---|
| **Exhibit<br> Number** | **Description of Documents** |
| [4.1](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex3-2_terres.htm) | [Certificate of Incorporation of Terrestrial Energy Inc. (incorporated herein by reference to Exhibit 3.2 filed with the Current Report on Form 8-K (Reg. No. 001-42252) filed by the registrant on November 3, 2025).](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex3-2_terres.htm) |
| [4.2](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex3-3_terres.htm) | [Bylaws of Terrestrial Energy Inc. (incorporated herein by reference to Exhibit 3.3 filed with the Current Report on Form 8-K (Reg. No. 001-42252) filed by the registrant on November 3, 2025).](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex3-3_terres.htm) |
| [5.1\*](tm2534292d1_ex5-1.htm) | [Opinion of Bryan Cave Leighton Paisner LLP.](tm2534292d1_ex5-1.htm) |
| [10.1](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex10-9_terres.htm) | [Terrestrial Energy Inc. 2025 Equity Incentive Plan, dated as of October 28, 2025 (incorporated herein by reference to Exhibit 10.9 filed with the Current Report on Form 8-K (Reg. No. 001-42252) filed by the registrant on November 3, 2025).](https://www.sec.gov/Archives/edgar/data/2019804/000121390025105304/ea026338601ex10-9_terres.htm) |
| [10.2\*](tm2534292d1_ex10-2.htm) | [Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan.](tm2534292d1_ex10-2.htm) |
| [23.1\*](tm2534292d1_ex23-1.htm) | [Consent of UHY LLP.](tm2534292d1_ex23-1.htm) |
| [23.2\*](tm2534292d1_ex23-2.htm) | [Consent of WithumSmith+Brown, PC.](tm2534292d1_ex23-2.htm) |
| [23.3\*](tm2534292d1_ex5-1.htm) | [Consent of Bryan Cave Leighton Paisner (included in Exhibit 5.1 to this Registration Statement).](tm2534292d1_ex5-1.htm) |
| [24.1\*](#a_001) | [Power of Attorney (included on the signature page to this Registration Statement).](#a_001) |
| [107\*](tm2534292d1_ex-filingfees.htm) | [Filing Fee Table.](tm2534292d1_ex-filingfees.htm) |

---

\* Filed herewith.

**Item 9. Undertakings.**

(a) The
undersigned Registrant hereby undertakes:

(1) to
file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) to include any prospectus required by Section 10(a)(3) of the Securities Act;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) to reflect in the prospectus any facts or events arising after the effective date of this Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in this Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) to include any material information with respect to the plan of distribution not previously disclosed in this Registration Statement or any material change to such information in this Registration Statement;

*provided, however*, that paragraphs (1)(i) and (1)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in this Registration Statement;

(2) that,
for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to
be the initial bona fide offering thereof; and

(3) to
remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination
of the offering.

(b) The
undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated
by reference in this Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) Insofar
as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission
such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that
a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director,
officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel
the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification
by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

**SIGNATURES**

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Charlotte, State of North Carolina, on January 2, 2026.

---

| | |
|:---|:---|
| **TERRESTRIAL ENERGY INC.** | **TERRESTRIAL ENERGY INC.** |
| By: | /s/ Brian Thrasher |
| Name: | Brian Thrasher |
| Title: | Chief Financial Officer |

---

**POWER OF ATTORNEY**

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Simon Irish, Brian Thrasher and Steven Millsap and each of them singly (with full power to each of them to act alone), the individual's true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution in each of them, for the person and in his or her name, place and stead, and in any and all capacities, to sign any and all amendments or supplements to this Registration Statement, including any post-effective amendments, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite or necessary to be done in and about the premises, as full to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

---

| | | |
|:---|:---|:---|
| **Signature** | **Title** | **Date** |
| /s/ Simon Irish | Chief Executive Officer and Director | January 2, 2026 |
| Simon Irish | (*Principal Executive Officer*) |  |
| /s/ Brian Thrasher | Chief Financial Officer | January 2, 2026 |
| Brian Thrasher | (*Principal Financial and Accounting Officer*) |  |
| /s/ Frederick Buckman | Chairman of the Board of Directors | January 2, 2026 |
| Frederick Buckman |  |  |
| /s/ Shawn Matthews | Director | January 2, 2026 |
| Shawn Matthews |  |  |
| /s/ Hugh MacDiarmid | Director | January 2, 2026 |
| Hugh MacDiarmid |  |  |
| /s/ David Hill | Director | January 2, 2026 |
| David Hill |  |  |
| /s/ Charles Pardee | Director | January 2, 2026 |
| Charles Pardee |  |  |
| /s/ Robert W. Jones | Director | January 2, 2026 |
| Robert W. Jones |  |  |
| /s/ William Johnson | Director | January 2, 2026 |
| William Johnson |  |  |
| /s/ David LeBlanc | Chief Technology Officer and Director | January 2, 2026 |
| David LeBlanc |  |  |

---

## Exhibit 5.1

**Exhibit 5.1**

---

| | |
|:---|:---|
| <br> January 2, 2026<br>Terrestrial Energy Inc.<br> 2730 W. Tyvola Road, Suite 10,<br> Charlotte, NC 28217<br>| ![](tm2534292d1_ex5-1img001.jpg) |

---

---

| | |
|:---|:---|
| **Re:** | **Terrestrial Energy Inc.<br> Registration Statement on Form S-8** |

---

Ladies and Gentlemen:

We have acted as special counsel to Terrestrial Energy Inc., a Delaware corporation (the "Company"), in connection with a Registration Statement on Form S-8 (the "Registration Statement"), being filed by the Company on the date hereof with the Securities and Exchange Commission (the "SEC") under the Securities Act of 1933, as amended (the "Securities Act"), relating to the registration of up to 34,152,299 shares (the "Shares") of Common Stock, $0.0001 par value per share (the "Common Stock"), which may be issued pursuant to the Company's Second Amended and Restated 2024 Stock Option Plan (the "Legacy Plan") and the 2025 Equity Incentive Plan (the "2025 Plan", and together with the Legacy Plan, the "Plans").

In connection herewith, we have examined:

(1) the Registration Statement;

(2) the Plans;

(3) the Second Amended and Restated Certificate of Incorporation
of the Company, as amended; and

(4) the Amended and Restated Bylaws of the Company.

We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such other corporate records, agreements and instruments of the Company, statements and certificates of public officials and officers of the Company, and such other documents, records and instruments, and we have made such legal and factual inquiries, as we have deemed necessary or appropriate as a basis for us to render the opinions hereinafter expressed. In our examination of the foregoing, we have assumed the genuineness of all signatures, the legal competence and capacity of natural persons, the authenticity of documents submitted to us as originals and the conformity with authentic original documents of all documents submitted to us as copies or by facsimile or other means of electronic transmission, or which we obtained from the SEC's Electronic Data Gathering, Analysis and Retrieval system ("EDGAR") or other sites maintained by a court or governmental authority or regulatory body and the authenticity of the originals of such latter documents. If any documents we examined in printed, word processed or similar form have been filed with the SEC on Edgar or such court or governmental authority or regulatory body, we have assumed that the document so filed is identical to the document we examined except for formatting changes. When relevant facts were not independently established, we have relied without independent investigation as to matters of fact upon statements of governmental officials and upon representations made in or pursuant to the certificates and statements of appropriate representatives of the Company.

In connection herewith, we have assumed that, other than with respect to the Company, all of the documents referred to in this opinion letter have been duly authorized by, have been duly executed and delivered by, and constitute the valid, binding and enforceable obligations of, all of the parties to such documents, all of the signatories to such documents have been duly authorized and all such parties are duly organized and validly existing and have the power and authority (corporate or other) to execute, deliver and perform such documents.

---

| | |
|:---|:---|
| Terrestrial Energy Inc.<br> January 2, 2026<br> Page 2 | ![](tm2534292d1_ex5-1img002.jpg) |

---

Based upon the foregoing and in reliance thereon, and subject to the assumptions, comments, qualifications, limitations and exceptions set forth herein, we are of the opinion that the Shares have been duly authorized for issuance and upon issuance and delivery of the Shares upon payment therefor, in accordance with the terms of the Plans and any relevant agreements thereunder, the Shares will be validly issued, fully paid and non-assessable.

In rendering the opinion stated herein, we have also assumed that: (a) each award agreement under which options are granted pursuant to the Plans will be consistent with the applicable Plan and will be duly authorized, executed and delivered by the parties thereto, and (b) the consideration received by the Company for each of the Shares delivered pursuant to the Plans shall not be less than the per share par value of the Shares.

This opinion is not rendered with respect to any laws other than the General Corporation Law of the State of Delaware. The opinions set forth herein are made as of the date hereof and are subject to, and may be limited by, future changes in the factual matters set forth herein, and we undertake no duty to advise you of the same. The opinions expressed herein are based upon the law in effect (and published or otherwise generally available) on the date hereof, and we assume no obligation to revise or supplement these opinions should such law be changed by legislative action, judicial decision or otherwise. In rendering our opinions, we have not considered, and hereby disclaim any opinion as to, the application or impact of any laws, cases, decisions, rules or regulations of any other jurisdiction, court or administrative agency.

This opinion letter is being delivered by us in connection with the filing of the Registration Statement with the SEC. We do not render any opinions except as set forth above. We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement. We also consent to your filing copies of this opinion letter as an exhibit to the Registration Statement with such agencies of such jurisdictions as you deem necessary in the course of complying with the laws of such jurisdictions regarding the offering and sale of the Shares. In giving such consent, we do not thereby concede that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the SEC promulgated thereunder.

Very truly yours,

/s/ Bryan Cave Leighton Paisner LLP

Bryan Cave Leighton Paisner LLP

## Exhibit 10.2

**Exhibit 10.2**

**TERRESTRIAL ENERGY INC.**

**SECOND AMENDED AND RESTATED**

**2024 STOCK OPTION PLAN**

1 **Purpose and Background**.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) The purpose of this Terrestrial Energy
 Inc. Second Amended and Restated 2024 Stock Option Plan (the "**Plan**") is
 to advance the interests of Terrestrial Energy Inc., a Delaware corporation (the "**Corporation** "),
 and its Subsidiaries, by (i) encouraging the directors, officers, employees and consultants
 of the Corporation and its Subsidiaries to acquire shares in the Corporation, thereby increasing
 their proprietary interest in the Corporation; (ii) encouraging them to remain associated
 with the Corporation and its Subsidiaries; and (iii) furnishing them with additional
 incentive in their efforts on behalf of the Corporation and its Subsidiaries in the conduct
 of their affairs.

For these purposes, "**Subsidiary**" is defined as any corporation more than 50% of the outstanding voting securities of which are owned by the Corporation or any other subsidiary, directly or indirectly, or a partnership or limited liability company in which the Corporation or any subsidiary is a general partner or manager or holds interests entitling it to receive more than 50% of the profits or losses of the partnership or limited liability company.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) In addition to the ongoing purpose set
 forth above, the Corporation adopted this Plan to grant substitute options in connection
 with the redomestication of Terrestrial Energy Inc. to Delaware to individuals who previously
 held options to acquire shares under the Terrestrial Energy Inc. Amended and Restated 2014
 Stock Option Plan (the "**TEI Plan** "). For the avoidance of doubt, any directors,
 officers, employees or consultants of Terrestrial Energy (Ontario) Inc. f/k/a Terrestrial
 Energy Inc. ()"**TEI**") who held options to acquire shares under the TEI Plan
 were eligible to receive substitute options under this Plan as of the initial effective date
 of this Plan.

2 **Administration and Granting of Options**.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) The Plan shall be administered by the
 board of directors of the Corporation (the "**Board** "); provided, that the
 Board may delegate administration of the Plan or certain of its powers of administration
 to a committee of three members of the Board (the "**Committee** "). The Board
 may abolish the Committee at any time and revest in the Board the administration of the Plan.
 The members of the Committee shall be appointed by and serve at the pleasure of the Board.
 From time to time, the Board may increase or decrease the size of the Committee, add additional
 members to, remove members (with or without cause) from, appoint new members in substitution
 therefor, and fill vacancies, however caused, in the Committee. The Committee shall act pursuant
 to a vote of the majority of its members or, in the case of a Committee comprised of only
 two members, the unanimous consent of its members, whether present or not, or by the written
 consent of the majority of its members. Subject to any limitations prescribed by the Plan and
 the Board, the Committee may establish and follow such rules and regulations for the
 conduct of its business as it may determine to be advisable.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) The Board and each member thereof, and
 any person acting pursuant to authority delegated by the Board, (i) shall be entitled,
 in good faith, to rely or act upon any report or other information furnished by any executive
 officer, other officer or employee of the Corporation or its Subsidiaries, or the Corporation's
 auditors, consultants or any other agents assisting in the administration of the Plan; (ii) shall
 not be personally liable for any action or determination taken or made in good faith with
 respect to the Plan; and (iii) shall, to the extent permitted by law, be fully indemnified
 and protected by the Corporation with respect to any such action or determination. The determinations,
 interpretations and other actions of the Board pursuant to the provisions of the Plan shall
 be binding and conclusive for all purposes and on all persons.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c) The Board hereby expressly delegates to
 the Committee the authority to designate from time-to-time directors, officers, employees
 or consultants of the Corporation or any Subsidiary (the "**Optionees** ")
 to whom options to purchase authorized but unissued common shares of the Corporation (the
 "**Common Shares**") may be granted, the number of Common Shares to be optioned
 to each, and the terms and conditions applicable to any such option with the exception of
 the exercise price of the Common Shares covered by each option, subject in all events to
 the limits set forth in Sections 3 and 4.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(d) Every option granted under this Plan shall
 be evidenced by a written agreement between the Corporation and the relevant Optionee, and
 any notices or amendments related thereto (each, an "**Option Agreement** ")
 and the provisions of each Option Agreement shall conform to and be governed by this Plan.
 Only options granted under the TEI Plan that were intended to be and specified as incentive
 stock options subject to Section 422 of the Internal Revenue Code (collectively, "Incentive
 Stock Options") and which have been subsequently been substituted under this Plan may
 be Incentive Stock Options hereunder, and no further Incentive Stock Options may be granted
hereunder. Thus Incentive Stock Options may be held only by those individuals who hold Incentive Stock Options as of the initial effective
date of this Plan. In the event of any discrepancy between the terms of an Option Agreement and this Plan, the terms of this Plan shall
govern, provided, that, in the case of any Option Agreement which is issued (as determined by the Committee in its absolute discretion)
to any Optionee who is subject to taxation in the United States, the Committee shall have discretion to agree to terms which differ from
the Plan to the extent that the number of options granted does not exceed the number specified in Section 3, as amended from time
to time by resolution of the Corporation, and such terms are in compliance with applicable laws. For the avoidance of doubt, (i) the
terms contained in the Option Agreement of each Incentive Stock Option granted under the TEI Plan and substituted hereunder are hereby
incorporated into this Plan by reference and (ii) no provision in this Plan that would increase the rights available under any Incentive
Stock Option shall apply to any Incentive Stock Option.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(e) The Board or Committee, as applicable,
 shall in exercising its discretion under the Plan comply with all contractual obligations
 of the Corporation in effect from time to time, whether contained in the Corporation's
 Certificate of Incorporation or Bylaws.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(f) Each option shall be subject to the requirement
 that, if at any time counsel to the Corporation shall advise that the listing, registration
 or qualification of the Common Shares subject to such option upon any securities exchange
 or under any state or federal law, or the consent or approval of any governmental or regulatory
 body, is necessary as a condition of, or in connection with, the issuance or purchase of
 Common Shares thereunder, such option may not be accepted or exercised in whole or in part
 unless such listing, registration, qualification, consent or approval shall have been effected
 or obtained on conditions acceptable to the Board. Nothing herein shall be deemed to require
 the Corporation to apply for or to obtain such listing, registration or qualification.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(g) An Option Agreement may include a provision
 whereby the Corporation may elect to repurchase all or any part of the Common Shares acquired
 by the Optionee. Unless otherwise determined by the Board and subject to compliance with
 applicable laws, the repurchase price will be the fair market value of the Common Shares
 on the date of repurchase. An Option Agreement may also include a provision whereby the Corporation
 may elect to exercise a right of first refusal following receipt of notice from the Optionee
 of the intent to transfer all or any part of the Common Shares received under the option.
 Except as expressly provided in this paragraph or in the Option Agreement, such right of
 first refusal shall otherwise comply with any applicable provisions of the bylaws of the
 Corporation. The Board reserves the right to assign the Corporation's rights of repurchase
 and first refusal.

3 **Common Shares Subject to Plan**. Subject to adjustment under Section 13, the aggregate number of Common Shares to be delivered upon the exercise of all options granted under the Plan shall not exceed 412,375 Common Shares at the time of any granting of options, or any lesser maximum number of Shares permitted under the rules of any stock exchange on which the Common Shares are listed, if any, or by any other regulatory body having jurisdiction (in either case, an "**Authority**"). Further, the maximum number of Common Shares that may be issued under Incentive Stock Options is 142,500; provided, that only options granted under the TEI Plan that were intended to be Incentive Stock Options and have subsequently been substituted under this Plan may be Incentive Stock Options hereunder. If any option granted under this Plan shall expire or terminate for any reason without having been exercised in full, the unpurchased Common Shares that were subject to the expired or terminated option shall again be available for the purpose of this Plan. In addition, any Common Shares that are withheld for the payment of taxes or received by the Corporation as payment of the exercise price of an option, shall again be available for the purpose of this Plan.

4 **Number of Optioned Shares**. Subject to adjustment under Section 13 the number of Common Shares subject to an option to an Optionee shall be determined by the Committee, but no Optionee shall be granted an option which exceeds the maximum number of Common Shares permitted by any Authority.

5 **Vesting**. The Committee may, in its discretion, determine the time during which options shall vest and the method of vesting or that no vesting restriction shall exist. Vesting terms will be set out in each Optionee's Option Agreement. Unvested options may not be exercised following the Termination of Service Date (as defined below).

For the purposes of this Plan, the "**Termination of Service Date**" means date on which an Optionee ceases to provide Services as a result of the termination of the Optionee's employment or engagement with the Corporation or any Subsidiary for any reason, including death, retirement, resignation, involuntary termination with or without cause, or as a result of a disability. For the purposes of this definition and the Plan, an Optionee's employment or engagement with the Corporation or any Subsidiary shall be considered to have terminated on the last day of the Optionee's Services with the Corporation or any Subsidiary, as the case may be, whether such day is selected by agreement with the Optionee, or unilaterally by the Optionee or the Corporation or any Subsidiary, and whether with or without advance notice to the Optionee.

6 **Participation**. The Committee shall determine to whom options shall be granted, the terms and provisions of the respective Option Agreements, the time or times at which such options shall be granted and the number of Common Shares to be subject to each option. An individual who has been granted an option may, if he is otherwise eligible, and if permitted by any Authority, be granted an additional option or options if the Committee shall so determine.

7 **Exercise Price.** The exercise price of the Common Shares covered by each option shall be determined by the Board. Unless specifically determined otherwise by the Board, the exercise price for each option granted following the date of adoption of the Plan shall not be less than the fair market value of the Common Shares on the date of grant, as determined by the Board acting in good faith in accordance with (i) the requirements of Section 409A of the Code ("Section 409A") for Optionees who are subject to taxation in the United States, or (ii) such other applicable legal requirements with respect to Optionees who are not subject to taxation in the United States.

8 **Option Period, Consideration and Payment**.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) Subject to paragraph (b), each option
 shall be exercisable during the period beginning when that option vests and ending at the
 time, if any, fixed by the Committee and specified in the Option Agreement relating to that
 option, but in no case to exceed any maximum period permitted by any Authority. If no expiry
 date is set out in the Option Agreement, each option will expire 20 years after its grant
 date; provided, however, that any Incentive Stock Option will expire 10 years after its grant
 date (except with respect to an Optionee owning more than 10% of the voting power of the
 Corporation), in which case, any Incentive Stock Option will expire five years after its
 grant date).

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) Except as permitted under Sections 11
 and 15, no option may be exercised by a person who is not an Optionee.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c) The exercise of any option will be contingent
 upon receipt by the Corporation at its headquarters of a written notice of exercise, specifying
 the number of vested Common Shares with respect to which the option is being exercised. The
 notice of exercise must be accompanied by cash, certified check, bank draft, money order
 or electronic payment for the full purchase price of such Common Shares with respect to which
 the option is exercised. Subject to the approval of the Board, and only with respect to options
 that are not Incentive Stock Options, the Optionee may, but is not required to, "net
 exercise" such option such that the Optionee shall receive the number of vested Common
 Shares with respect to which the option is being exercised, reduced by the number of vested
 Common Shares with respect to which the option would be exercised but are required to cover
 the sum of the aggregate exercise price and any taxes required or permitted to be withheld
 in connection with the option's exercise.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(d) No Optionee or his legal representatives
 will be, or will be deemed to be, a holder of any Common Shares subject to an option under
 this Plan unless and until the certificates or appropriate book entry or electronic registration
 for such Common Shares are issued to or entered on behalf of such persons under the terms
 of the Plan, which shall be done expeditiously on request.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(e) Notwithstanding any other provision of
 this Plan, no option may be exercised unless the Optionee enters into a shareholders'
 agreement, if any, then in force with respect to the governance of the Corporation and its
 shareholders.

9 **Tax Withholdings.** The Corporation or any Subsidiary, as the case may be, may withhold any amount considered by the Corporation or any Subsidiary to be required by any taxing or other Authority to be withheld or paid by the Optionee and shall remit such amount to the taxing or other Authority on behalf of the Optionee. Unless "net exercise" is permitted in the Board's discretion pursuant to Section 8(c), if the Optionee's compensation is insufficient to cover the applicable amount in full, the Optionee shall remit the any outstanding amount by cash, certified check, bank draft, money order or electronic payment.

10 **Ceasing to be a Director, Officer, Employee or Consultant**.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) If an Optionee ceases to be a director,
 officer, employee or consultant of the Corporation or any Subsidiary for any reason other
 than the death of the Optionee, the Optionee's unvested options shall immediately terminate
 on the Termination of Service Date and the Optionee's vested options may be exercised
 until the earlier of (i) the expiry date or (ii) the end of any applicable post-termination
 period set forth in the Option Agreement (e.g., with respect to any Incentive Stock Option).

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) Nothing contained in the Plan or in any
 option granted pursuant to the Plan gives any Optionee any right to continue acting as a
 director, officer, employee or consultant of the Corporation or any Subsidiary.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c) An Optionee shall have no entitlement
 to damages or other compensation whatsoever arising from, in lieu of, or related to not receiving,
 any options which would have vested or been granted after the Termination of Service Date including but not limited
to damages in lieu of notice of termination at common law or civil law and each Optionee waives their rights to any such entitlements.

11 **Death of an Optionee.** Unless specifically contemplated in an Option Agreement that an Optionee's unvested options will vest upon the date of death of such Optionee, no unvested options will vest upon or after the date of death of an Optionee. An Optionee's vested options may be exercised by the executor of such deceased Optionee.

12 **Cash in Lieu of Shares**. Optionees who are not subject to taxation in the United States may elect to surrender their options to the Corporation in exchange for payment in Common Shares (or with the consent of the Board, in cash), calculated with reference to the fair market value of the Common Shares at the time of exercise minus the exercise price and any applicable withholdings, and the Board may specify the circumstances under which such election will be available, the manner in which such election may be exercised, and the manner in which the fair market value of the Common Shares will be determined.

13 **Adjustments.** If after the initial approval of the Plan, the Corporation subdivides, consolidates or reclassifies any of its Common Shares, pays stock dividends or reorganizes or causes a material reorganization of the capital of the Corporation (the "**Reorganization**"), the Corporation shall make any appropriate adjustments to the number of Common Shares optioned or to the option price per Common Share, or both, in respect of options granted or to be granted or both, as the circumstances may require to provide the Optionee with the same approximate rights vis a vis the Corporation's outstanding capital as such Optionee would have had if no such Reorganization had occurred. Notwithstanding the foregoing, no adjustment provided for under this Section 13 shall require the Corporation to sell or otherwise issue a fractional Common Share under any option, and the total adjustment with respect to any option shall be limited by deleting any fractional Common Share.

14 **Liquidity Event.** Notwithstanding any other provision of this Plan, in the event of an actual or potential Liquidity Event, the Board may, in its discretion, without the necessity or requirement for the agreement of any Optionee: (a) accelerate, conditionally or otherwise, on such terms as it sees fit, the vesting of any option; (b) permit the conditional exercise of any option, (c) otherwise amend or modify the terms of the options to assist the Optionees to tender the underlying Common Shares to, or participate in, the actual or potential Liquidity Event or to obtain the advantage of holding the underlying Common Shares during such Liquidity Event; (d) with respect to options held by an Optionee who is not subject to taxation in Canada, terminate, following the successful completion of such Liquidity Event, on such terms as it sees fit, the options not exercised prior to the successful completion of such Liquidity Event in exchange for a payment, in such form as may be determined by the Board, equal to the excess, if any, of (1) the value of the Common Stock the Optionee would have received in the Liquidity Event in respect of the Common Stock issuable to the Optionee upon the exercise of the option, over (2) any exercise price payable by such Optionee in connection with such exercise, subject to required withholdings, or (e) with respect to options held by an Optionee who is subject to taxation in Canada, provide that (A) the Optionee may elect to surrender any vested and exercisable options to the Corporation in consideration for a cash payment equal to the excess, if any, of (1) the value of the Common Stock the Optionee would have received in the Liquidity Event in respect of the Common Stock issuable to the Optionee upon the exercise of the option, over (2) any exercise price payable by such Optionee in connection with such exercise, subject to required withholdings, whereupon such Options will be deemed to have been cancelled (and in the event of such a surrender, the Corporation will duly and timely file an election in respect thereof under subsection 110(1.1) of the *Income Tax Act* (Canada), where applicable), and (B) if the Optionee elects not to surrender any options as set forth in (A) above or otherwise does not exercise such options prior to the completion of the Liquidity Event, all such unexercised options held by such Optionee will terminate and expire immediately prior to the closing of the Liquidity Event. For the avoidance of doubt, the payments described in (d) and (e) above will be zero if the value of the Common Stock issuable to the Optionee upon exercise of the option in connection with the Liquidity Event is equal to or less than the exercise price of such option.

For these purposes, a "**Liquidity Event**" means (a) a transaction, whether by way of a take-over bid, amalgamation, plan of arrangement, sale of securities, sale of all or substantially all of the assets or otherwise and whether for cash or non-cash consideration, pursuant to which (i) in the case of any transaction other than a sale of all or substantially all of the assets of the Corporation, at least 50% of the interests in the Corporation are, directly or indirectly, disposed of by the shareholders or (ii) in the case of a sale of assets, the offeror acquires all or substantially all of the assets of the Corporation; (b) an initial public offering of the Corporation, resulting in the holding by the public of Common Shares of the Corporation (or its successor entity), or a transaction giving rise to a stock exchange listing; or (c) the commencement of a liquidation of the Corporation.

15 **Non-Transferability.** All benefits, rights and options accruing to the Optionee in accordance with the terms and conditions of the Plan shall not be transferable or assignable except as specifically permitted by this Plan. Any benefits, rights and options may be exercised only by the Optionee or the Optionee's legal representative on death.

16 **Amendment and Termination of Plan.** The Board may, at any time, amend, modify, suspend, or terminate the Plan, subject to such approvals as may be required under the rules of any Authority, and provided that any amendment or modification does not materially adversely affect, in the Board's determination acting reasonably, the terms of any options granted under the Plan before that time. Options outstanding at the time of the Plan's termination may continue to vest or be exercised in accordance with their terms.

17 **Necessary Approvals.** If any Common Shares cannot be issued to an Optionee for legal or other legitimate reasons, in the Board's determination acting reasonably, the obligation of the Corporation to issue such Common Shares shall terminate and any option exercise price paid to the Corporation will be returned to the Optionee.

18 **No Rights as Shareholder.** The Optionee has no rights as a shareholder in respect of any of the optioned Common Shares (including any right to receive dividends or other distribution therefrom or thereon) except in respect of which the option has been properly exercised in accordance with the terms of the Option Agreement and this Plan.

19 **Effective Date of Plan.** This Plan shall become effective upon its approval by the Board, provided, that approval by the Corporation's shareholders must occur before the first anniversary of the date the Plan is adopted by the Board.

20 **Governing Law.** The Plan and all Option Agreements hereunder shall be construed in accordance with and governed by the laws of the State of Delaware excluding its conflict of laws rules.

21 **U.S. Optionees**. Notwithstanding anything in this Plan to the contrary, with respect to Optionees who are subject to taxation in the United States:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) The Plan and options granted under the
 Plan will be interpreted to the greatest extent possible in a manner that makes the Plan
 and the options exempt from Section 409A, and to the extent not so exempt, in compliance
 with the requirements imposed by Section 409A. If any Plan provision or option would
 result in the imposition of an additional tax under Section 409A, the Corporation and
 the Optionee intend that the Plan provision or option will be reformed to avoid imposition,
 to the extent possible, of the applicable tax and no action taken to comply with Section 409A
 shall be deemed to adversely affect the Optionee's rights to an option, provided, that,
 such intent and related reformation shall not apply to any Option Agreement that intentionally
 provides for the grant of an option that is subject to and noncompliant with Section 409A.
 Each Optionee further agrees that the Board, in the exercise of its sole discretion and without
 the consent of the Optionee, may amend or modify an option in any manner and delay the payment
 of any amounts payable pursuant to an option to the minimum extent necessary to meet the
 requirements of Section 409A as the Board deems appropriate or desirable, provided,
 that, such unilateral amendment or modification right shall not apply to any Option Agreement
 that intentionally provides for the grant of an option that is subject to and noncompliant
 with Section 409A. Notwithstanding anything in this Plan to the contrary, no option
 held by a U.S. taxpayer that is deemed to be subject to Section 409A shall be payable
 solely due to a Liquidity Event, unless such event also meets the requirements for a "change
 in ownership" or a "change in control" within the meaning of Section 409A.
 Except as provided in any agreement between the Corporation and an Optionee, notwithstanding
 the foregoing, none of the Corporation, the Board, or the Committee shall have any obligation
 to take any action to prevent the assessment of any additional tax or penalty on any Optionee
 under Section 409A and none of the Corporation, the Board, or the Committee will have
 any liability to any Optionee for such tax or penalty unless such obligation is expressly
 set forth in the applicable Option Agreement.

Only employees of TEI may have been granted options under the TEI Plan that were intended to be Incentive Stock Options and have been substituted hereunder. In no event shall the Corporation have any obligation or liability to an Optionee if an option is determined not to qualify as an Incentive Stock Option. If an Optionee makes a disposition (as defined in Section 424(c) of the Code) of any Common Shares acquired pursuant to the exercise of an Incentive Stock Option prior to the expiration of two years from the date on which the Incentive Stock Option was granted or prior to the expiration of one year from the date on which the Incentive Stock Option was exercised, the Optionee shall send written notice to the Corporation of the date of such disposition, the number of Common Shares disposed of, the amount of proceeds received from such disposition, and any other information relating to such disposition as the Corporation may reasonably request. The Optionee shall, in the event of such a disposition, make appropriate arrangements with the Corporation to provide for the amount of any additional withholding required by Sections 3102 and 3402 of the Code and applicable State income tax laws.

## Exhibit 23.1

**Exhibit 23.1**

**INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM'S CONSENT**

We consent to the incorporation by reference in the Registration Statement of Terrestrial Energy Inc. (the "Company") on Form S-8 of our report on the consolidated financial statements of the Company dated May 30, 2025, which includes an explanatory paragraph as to the Company's ability to continue as a going concern, with respect to our audits of the consolidated financial statements of the Company as of December 31, 2024 and 2023 and for the two-year period ended December 31, 2024.

/s/ UHY LLP

Melville, NY

January 2, 2026

## Exhibit 23.2

**Exhibit 23.2** 

**CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM**

We hereby consent to the incorporation by reference in the Prospectus constituting a part of this Registration Statement on Form S-8 of our report dated March 31, 2025, except for the effects of the Restatement disclosed in Note 2, as to which the date is July 17, 2025, relating to the financial statements of HCM II Acquisition Corp., as of December 31, 2024 and the period from April 4, 2024 (inception) through December 31, 2024, which includes an explanatory paragraph as to HCM II Acquisition Corp.'s ability to continue as a going concern described in Note 1 to the financial statements.

/s/ WithumSmith+Brown, PC

New York, New York

January 2, 2026

## Ex-Filing

?xml version='1.0' encoding='ASCII'? EX-FILING FEES

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| |
|:---|
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Calculation of Filing Fee Tables**  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **S-8**  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Terrestrial Energy Inc. /DE/**  |

---

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| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Security Type**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Security Class Title**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Fee Calculation Rule**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Amount Registered**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Proposed Maximum Offering Price Per Unit**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Maximum Aggregate Offering Price**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Fee Rate**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Amount of Registration Fee**  |
| 1 | Equity | Common Stock, $0.0001 par value per share | Other | 18678584 | $6.135 | $114593112.84 | 0.0001381 | $15825.31 |
| 2 | Equity | Common Stock, $0.0001 par value per share | Other | 15473715 | $6.135 | $94931241.52 | 0.0001381 | $13110.00 |
| Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: |  | $209524354.36  |  | $28935.31  |
| Total Fee Offsets:  | Total Fee Offsets:  | Total Fee Offsets:  | Total Fee Offsets:  | Total Fee Offsets:  |  |  |  | $0.00  |
| Net Fee Due:  | Net Fee Due:  | Net Fee Due:  | Net Fee Due:  | Net Fee Due:  |  |  |  | $28935.31  |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Offering Note** <br>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <sup>1</sup> Note 1.a Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall also cover any additional shares of the Registrant's common stock, $0.0001 par value per share ("Common Stock") that may become issuable under the terms of (i) the Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan (the "Legacy Plan") and (ii) the Terrestrial Energy Inc. 2025 Equity Incentive Plan (the "2025 Plan"), in each case by reason of any share split, share dividend, recapitalization or other similar transaction effected without the Company's receipt of consideration which results in an increase in the number of the outstanding shares of Common Stock. Note 1.b Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(c) and (h) under the Securities Act, based on the average of the high and low sales prices of the Common Stock on the Nasdaq Stock Market on December 31, 2025. Note 1.c Represents shares of Common Stock issuable upon the exercise of outstanding options under the Legacy Plan as of the date of this Registration Statement. Note 1.d The Registrant does not have any fee offsets to claim.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <sup>2</sup> See Offering Note 1.a, 1.b and 1.d Note 2.a Represents shares of Common Stock authorized for future issuance under the 2024 Plan as of the date of this Registration Statement.

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| | |
|:---|:---|
| | |
| **Rule 457(p)** | **Rule 457(p)** |
| Fee Offset Claims | N/A |
| Fee Offset Sources | N/A |

---