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CORRESP
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 HCM II Acquisition Corp.

 100 First Stamford Place, Suite 330

 Stamford, CT 06902

 Terrestrial Energy Inc.

 2730 W. Tyvola Road, Suite 100

 Charlotte, NC 28217

 VIA EDGAR

 July
17, 2025

 U.S. Securities and Exchange Commission

 Division of Corporation Finance

 Office of Real Estate & Construction

 100 F Street, N.E.

 Washington, D.C. 20549

 Attention:

 Eiko Yaoita Pyles
 Hugh West
 Sarah Sidwell
 Jennifer Angelini

 Re:
 HCM II Acquisition Corp.

 Draft Registration Statement on Form S-4

 Submitted on May 30, 2025

 CIK No. 0002019804

 Ladies and Gentlemen:

 Terrestrial Energy (the " Company ")
and HCM II Acquisition Corp. (" HCM II " and collectively with the Company, " we ," " our "
or " us ") hereby transmit our response to the comment letter received from the staff (the " Staff ",
" you " or " your ") of the U.S. Securities and Exchange Commission (the " Commission "),
dated June 26, 2025, regarding the Draft Registration Statement on Form S-4 (the " Registration Statement ") confidentially
submitted to the Commission on May 30, 2025.

 For the Staff's convenience,
we have repeated below the Staff's comment in bold, and have followed each comment with our response. In response to the Staff's
comments, we are filing via Edgar a revised Registration Statement simultaneously with the submission of this response letter.

 Draft Registration Statement on Form S-4

 Cover Page

 1. Please state the amount of all compensation received or to be received by the Sponsor, its affiliates, and promotors on the cover
page. In this regard, we note references elsewhere to compensation to be received by Shawn Matthews and the independent directors (e.g.,
page 13). Refer to Item 1604(a)(3) of Regulation S-K.

 Response: We acknowledge the Staff's comment and have
revised the disclosure on the cover page to address the Staff's comment.

 2. Please briefly describe any material financing transactions that have occurred since the initial public offering. In this regard,
we note references elsewhere to (i) a $2,500,000 convertible promissory note issued to the Sponsor and (ii) working capital loans and
advances by the Sponsor and HCM II's officers and directors. Additionally revise your summary to discuss material terms of such financing
transactions. Please refer to Items 1604(a)(2) and 1604(b)(5) of Regulation S-K. File the promissory note and working capital loan agreement
as exhibits to your registration statement, or advise. Include relevant information within your compensation disclosures.

 Response: We acknowledge the Staff's comment on material financing
transactions and have revised the disclosure on the cover page to address the Staff's comment.

 Questions and Answers for Shareholders of HCM II

 Q. What equity stake will current HCM II shareholders and Terrestrial
Stockholders hold...?,

 page xviii

 3. Please revise to explain the terms "Terrestrial Energy Shareholders" and "Terrestrial Energy Debt Holders."
Revised disclosure should clarify how Terrestrial options, units, warrants, notes, and other outstanding securities are reflected for
ownership purposes (non-diluted and fully-diluted) and quantify underlying shares, identifying any needed assumptions. In this regard,
we note disclosure on page 255 that units issued in the 2024 bridge financing will receive additional shares based on the trading price
following the lock-up period. Please also clarify how shares issuable in connection with the recapitalization are treated for ownership
purposes throughout. Discuss the call options referenced on page F-64 in an appropriate section, including the related person transactions
section as applicable.

 Response: We acknowledge the Staff's
comment and have revised the tabular disclosure in the Q&A on pages xviii, xix, 17, 18, 21 and 58 to address the Staff's comment,
including to use the terms "Terrestrial Energy Stockholders" and "Holders of Terrestrial Convertible Notes" to
align with the terms already defined in the Registration Statement.

 Q. Why is HCM II proposing the Domestication?,
page xix

 4. We note that the Sponsor and independent directors hold 100% of the outstanding HCM II Class B Ordinary
Shares, and that only holders of the HCM II Class B Ordinary Shares may vote in connection with the Domestication Proposal. If approval
of the Domestication Proposal is assured, revise to state so specifically and to highlight that for investors.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on page xx to address the Staff's comment.

 Q. What conditions must be satisfied to complete
the Business Combination?, page xxvi

 5. We note the closing condition that the waiting period with the U.S. Nuclear Regulatory Commission (NRC)
has expired or has been terminated, but also disclosure on page 127 that the parties are not aware of any material regulatory approvals
or actions required for completion of the business combination, other than the antitrust filing and waiting period. Please revise to clearly
disclose whether or not an NRC filing and/or waiting period is required for the business combination. Additionally revise your disclosure
to clearly identify all material closing conditions (revising the reference to "certain") and to indicate which may be waived.

 Response: We respectfully advise the Staff that no NRC filing and/or
waiting period is required in connection with the consummation of the Business Combination. We have revised the disclosure on the cover
page as well as pages 37 – 39 and 125 to address the Staff's comment.

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 Q. Who is the Sponsor?, page xxx

 6. We note disclosure that the Sponsor is controlled by Shawn Matthews, and that Mr. Matthews has economic
interests of 51.3% in the Founder Shares and 18.1% in the Private Placement Warrants held by the Sponsor. Please revise to disclose that
the non-managing sponsor investors hold the remaining economic interests, if true, and revise or explain your disclosure that "No
other person has a direct or indirect material interest in the Sponsor." Refer to Item 1603(a)(7) of Regulation S-K. Additionally
disclose whether Mr. Matthews has sole management (including voting) control of the Sponsor. Reconcile disclosure here that, "Each
other director and officer of HCM II have economic interests in the Founder Shares and/or Private Placement Warrants held by the Sponsor,"
with disclosure on page 10 that, "No other director or officer of HCM II has economic interests in the Founder Shares/Private Placement
Warrants."

 Response: We acknowledge the Staff's comment and have revised the disclosure
on pages xxxi and xxxii to address the Staff's comment.

 7. We note disclosure that "HCM II's management believes MRNO represents a high-quality, public-ready company with an attractive
valuation" and "HCM I supported the HCM II transaction with extensive due diligence, significant investor outreach and comprehensive
planning." Please revise to clarify the relevance of the prior SPAC and target to this current transaction. To the extent that HCM
I has involvement in the current transaction, provide disclosure in the related person transactions section and elsewhere as appropriate.
We further note that a Form S-1 has been filed for HCM III's initial public offering; please update this section accordingly.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on page xxxii to address the Staff's comment.

 Summary of the Proxy Statement/Prospectus, page 1

 8. Please revise the diagram on page 3 to separately show the ownership of the Sponsor, other inside shareholders,
and public shareholders. Additionally show the PIPE shareholders.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages 2 and 3 to address the Staff's comment.

 Quorum and Vote of HCM II Shareholders, page
8

 9. Please revise to disclose the percentage of shares held by public shareholders that is required to
approve each proposal, clearly stating if none is required. In this regard, we note that 37.5% of Public Shares are required for the Business
Combination Proposal, but percentages are not disclosed for other proposals. We also note disclosure that, "If only the minimum number
of shares representing a quorum are voted, no additional shares would need to be voted in favor;" please revise to clearly state
the percentage of public shareholders needed to establish a quorum and whether any public shareholders are required to vote in favor.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages 10 and 11 to address the Staff's comment.

 Certain Interests of HCM II's Directors
and Officers..., page 10

 10. Please provide a brief summary of the conflicts of interest of the target company officers and directors
and unaffiliated security holders. Please refer to Item 1604(b)(3) of Regulation S-K.

 Response: We acknowledge the Staff's comment and have revised the disclosure
on page 15 – 16 as well as on pages 143 – 145 to address the Staff's comment.

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 11. We note disclosure that, since shares and warrants will be subject to lock-up restrictions, you believe
such securities have less value. Please remove or revise to more fully explain whether and how transfer restrictions affect value, including
whether the end of the lock-up period would restore full value.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on page 13 to address the Staff's comment.

 Compensation Received
by the Sponsor..., page 13

 12. Please revise the compensation table to include Mr. Matthews' appointment as a New Terrestrial
director, and additionally discuss this directorship on page 124. Specifically discuss the New Equity Incentive Plan here and/or on page
12 as appropriate; in this regard we note disclosure on page 147 regarding New Terrestrial management's personal interest in the Plan.
Quantify the New Terrestrial shares issuable to Mr. Matthews upon (i) conversion of the $4,000,000 Terrestrial Convertible Notes and (ii)
exercise of the 40,000 Terrestrial Warrants, identifying any necessary assumptions. Disclose the convertible promissory note issued to
the Sponsor, and quantify the outstanding working capital loans and reimbursable expenses as of the date of the proxy statement/prospectus,
consistent with disclosures elsewhere (e.g., pages 33, 215). Quantify amounts payable to sponsor under the administrative services agreement,
and clarify whether these are included within "reimbursable expenses."

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages xxxi, 13, 16, 17, 137 and 152 to address the Staff's comment.

 Dilution to HCM II's Shareholders, page 15

 13. Please address the following as it relates to your dilution disclosures:

 ● Update the dilution table to reflect the information as
of March 31, 2025 or the most recent balance sheet date of HCM II included in the filing.

 ● Revise the net tangible book value, as adjusted, amounts
to reflect the payment of deferred underwriting fees upon closing of the business combination.

 ● Revise to reflect the forward purchase agreement, including
potential impact of the forward purchases on Dilution calculations, if any.

 Response: We acknowledge the Staff's comment and have updated
the dilution table on pages 19 and 20 to reflect the information as of March 31, 2025.

 We respectively advise the Staff that
the deferred underwriting fees has already been accrued in HCM II's historical balance sheet as a liability. Upon consummation of
the Business Combination, the payment of the deferred underwriting fees will result in a corresponding reduction of cash and liabilities.
As such, the transaction will have no net impact on the net tangible book value as adjusted. Accordingly, we believe no revision is required
to the pro forma net tangible book value presented in the table.

 We respectively advise the Staff that
the 5,000,000 shares subject to the forward purchase agreement are presented in the PIPE shares line in the table. As such, the impact
of the forward purchase agreement has already been reflected in the dilution calculations, and no further revision is necessary.

 14. We note disclosure on page 77 that the Sponsor may convert working capital loans into 1,500,000 Warrants.
Please discuss, by footnote or otherwise, the contingent issuance of such Warrants and potential dilutive effects thereof.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages 19-23 to address the Staff's comment.

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 Background and Material Terms of the Business
Combination, page 18

 15. Please provide a summary of the material terms of the business combination. Please refer to Item 1604(b)(1)
of Regulation S-K.

 Response: We acknowledge the Staff's
comment and have added the disclosure on pages 23-41 to address the Staff's comment.

 Summary Risk Factors

 Risks Related to HCM II and the Business Combination,
page 22

 16. We note disclosure that the business combination is subject to the closing conditions that HCM II have
at least $5,000,0001 in net tangible assets and $150,000,000 in available cash ( e.g., page 174). Please include risk factor disclosure
regarding these closing conditions, including the impact on public shareholders in the event redemptions cause such conditions (and the
separate $75,000,000 million PIPE closing condition) not to be met. Expand the risk factor on pages 46-47 to additionally discuss the
consequences and related risks to public shareholders.

 Response: We acknowledge the Staff's
comment and have (i) added a risk factor on page 45 and (ii) revised the disclosure on pages 68 and 70 to address the Staff's comment.

 Risks Related to Our Business and Industry,
page 23

 17. Please revise to specifically disclose whether you are required to obtain NRC approval of the Integral
Molten Salt Reactor (IMSR) and discuss the consequences and related risks if such approval is not obtained. Revise disclosure on page
55 to clarify the regulatory status of your IMSR design (and/or its key components) compared with the other developers' designs
disclosed to be in "preapplication review with the NRC." In this regard, we note disclosure on page 70 that appears to indicate
you are not yet in "formal application review" and on page 229 that refers to a "pre-application phase."

 Response: We acknowledge the Staff's comment and have revised
the disclosure on pages 47, 48, 91, 92, 262 and 263 to address the Staff's comment.

 Risk Factors

 HCM II's shareholders will experience dilution...,
page 36

 18. Please expand your disclosure to more fully discuss the effects of dilution on nonredeeming public
shareholders, for instance under the maximum contractual redemption scenario.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages 58 and 59 to address the Staff's comment.

 The Warrant Agreement designates the courts...,
page 48

 19. We note that the exclusive forum provision in the warrant agreement applies to Securities Act claims.
Please revise to state that there is uncertainty as to whether a court would enforce such provision and that investors cannot waive compliance
with the federal securities laws and the rules and regulations thereunder. In that regard, we note that Section 22 of the Securities Act
creates concurrent jurisdiction for federal and state courts over all suits brought to enforce any duty or liability created by the Securities
Act or the rules or regulations thereunder. Include analogous disclosure on page 78 in relation to New Terrestrial's certificate of incorporation,
which provides the federal district courts will be the exclusive forum for Securities Act and Exchange Act claims.

 Response: We acknowledge the Staff's
comment and have revised the disclosure on pages 71 and 100 to address the Staff's comment.

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