C3is (CISS) F-1/ARegistration statement (foreign) (amended)

EXHIBIT 5.1

REEDER & SIMPSON, P.C.

ATTORNEYS AT LAW

May 17, 2023

C3is Inc.

331 Kifissias Avenue

Erithrea 14561

Athens, Greece

Re: C3is Inc. – Exhibit 5.1 Opinion

Ladies and Gentlemen:

We have acted as special Marshall Islands counsel to C3is Inc., a Republic of the Marshall Islands corporation (the “Company”), in connection with the preparation of the Company’s Registration Statement on Form F-1 (Reg. No. 333-271228) (as amended, the “Registration Statement”), originally filed with the U.S. Securities and Exchange Commission (the “Commission”), on April 12, 2023 under the Securities Act of 1933, as amended (the “Act”), including the prospectus that is part of the Registration Statement (the “Prospectus”). The Registration Statement and Prospectus relate to the distribution by Imperial Petroleum Inc. of 3,182,932 shares of common stock, par value $0.01 (the “Shares”), of the Company to holders of Imperial Petroleum Inc.’s common stock and holders of outstanding warrants to purchase Imperial Petroleum Inc. common stock on a pro rata basis.

As such counsel we have examined originals or copies (certified or otherwise identified to our satisfaction) of the following documents:

In such examination, we have assumed (a) the legal competence or capacity of persons or entities (other than the Company) to complete the execution of documents, (b) the genuineness of all signatures and the authenticity of all documents submitted to us as originals, (c) the conformity to original documents of all documents submitted to us as conformed or photostatic copies, (d) that the documents reviewed by us in connection with the rendering of the opinions set forth herein are true, correct and complete, and (e) the truthfulness of each statement as to all factual matters contained in any document or certificate encompassed within the due diligence review undertaken by us. As to matters of fact material to this opinion that have not been independently established, we have relied upon the representations and certificates of officers or representatives of the Company and of public officials, in each case as we have deemed relevant and appropriate. We have not independently verified the facts so relied on.

We have assumed that the Company will, at the time of any issuance of Shares and Warrant Shares, have a sufficient number of authorized but unissued Common Shares pursuant to its Articles.

This opinion letter is limited to Marshall Islands law and is as of the date hereof.

Based on the foregoing and having regard to the legal considerations which we deem relevant, we are of the opinion that:

(2)     The Shares, when issued as contemplated in the Registration Statement and Prospectus, will be validly issued, fully paid and nonassessable.

We consent to the filing of this opinion as an exhibit to the Registration Statement, the discussion of this opinion in the Registration Statement, and the references to our firm in the Prospectus. In giving this consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Act, or the rules and regulations promulgated thereunder, nor do we admit that we are experts with respect to any part of the Registration Statement within the meaning of the term “expert” as used in the Act.

Very truly yours,