Exhibit 5.1 

    Sullivan & Worcester LLP
1633 Broadway
New York, NY 10019

212 660 3000
sullivanlaw.com

April 29, 2022

Soluna Holdings, Inc.

325 Washington Avenue Extension

Albany, NY 12206

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

This opinion is furnished to you in connection with a final prospectus supplement, dated April 26, 2022 (the “Underwritten Final Prospectus Supplement”), and a final prospectus supplement dated April 26, 2022 (the “Registered Direct Final Prospectus Supplement” and, together with the Underwritten Final Prospectus Supplement, the “Final Prospectus Supplements”) to the prospectus forming a part of the registration statement on Form S-3 (File No. 333-261427), declared effective by the U.S. Securities and Exchange Commission (the “Commission”) on December 16, 2021 (as amended from time to time, the “Registration Statement”), which Final Prospectus Supplements were filed by Soluna Holdings, Inc., a Nevada corporation (the “Company”), with the Commission on April 29, 2022 under the Securities Act of 1933, as amended (the “Securities Act”), for the proposed offering of (i) up to an aggregate of 604,571 shares (the “Underwritten Preferred Shares”) of 9.0% Series A Cumulative Perpetual Preferred Stock, par value $0.001 per share, of the Company (the “Series A Preferred Stock”), which includes up to an aggregate of 78,857 shares of Series A Preferred Stock that may be issued to cover over-allotments, if any, in an underwritten public offering and (ii) an aggregate of 1,142,857 shares of Series A Preferred Stock to certain lenders in a concurrent registered direct offering (the “Registered Direct Preferred Shares” and, collectively with the Underwritten Preferred Shares, the “Shares”).

The Underwritten Preferred Shares are being offered solely under the Underwritten Final Prospectus Supplement pursuant to the Underwriting Agreement, dated April 26, 2022 (the “Underwriting Agreement”) by and among the Company and Univest Securities, LLC, as representative (the “Underwriter”) relating to an underwritten public offering. The Registered Direct Preferred Shares are being issued solely under the Registered Direct Final Prospectus Supplement in a registered direct offering by the Company to certain institutional lenders (the “Lenders”) pursuant to certain outstanding promissory notes in an aggregate principal amount of $20 million (the “Notes”), which Notes provide the Lenders with an option to elect that such Notes be repaid by the Company in shares of Series A Preferred Stock, resulting in an aggregate of 1,142,857 Shares issuable to the Lenders in full satisfaction of the Company’s obligations under the Notes and subscription agreements, each dated April 29, 2022, by and between the Company and each of the Lenders pursuant to which the applicable number of Registered Direct Shares are issuable to such Lenders (“Subscription Agreements”).

BOSTON   LONDON   NEW YORK   TEL AVIV   WASHINGTON, DC 

Soluna Holdings, Inc.
April 29, 2022
Page 2

We are acting as counsel for the Company in connection with the Final Prospectus Supplements and the Registration Statement. In connection with this opinion, we have examined and relied upon the originals or copies certified or otherwise identified to our satisfaction of the Final Prospectus Supplements, the Registration Statement, including the exhibits filed therewith, and have also examined and relied upon minutes of meetings and resolutions of the board of directors of the Company as provided to us by the Company, the articles of incorporation and bylaws of the Company, each as restated and/or amended to date (the “Charter Documents”), the Certificate of Designations, Preferences and Rights of Series A Preferred Stock, as amended, approved by the Company’s board of directors (the “Certificate of Designation”), and such other documents as we have deemed necessary for purposes of rendering the opinion hereinafter set forth. In connection with this opinion, we have assumed that the Shares will not be issued in violation of (a) any restriction or limitation contained in the Charter Documents or the Certificate of Designation or (b) any applicable law or result in a default under or breach of any agreement or instrument binding on the Company and will comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company.

In addition to the foregoing, we have relied as to matters of fact upon the representations made by the Company and its representatives. In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as copies, the authenticity of the originals of such latter documents and the legal competence of all signatories to such documents. Other than our examination of the documents indicated above, we have made no other examination in connection with this opinion.

We are members of the Bar of the State of New York. We do not hold ourselves out as being conversant with, or expressing any opinion with respect to, the laws of any jurisdiction other than the federal laws of the United States of America, the laws of the State of New York, and Chapter 78 of the Nevada Revised Statutes. Accordingly, the opinions expressed herein are expressly limited to the federal laws of the United States of America, the laws of the State of New York, and Chapter 78 of the Nevada Revised Statutes.

Based upon and subject to the foregoing, we are of the opinion that the Shares have been duly authorized for issuance by all necessary corporate action by the Company and, when issued and sold as described in the Registration Statement and the Final Prospectus Supplements and in accordance with the terms of the Certificate of Designation, will be validly issued, fully paid and non-assessable shares of Series A Preferred Stock.

This opinion letter speaks only as of the date hereof and we assume no obligation to update or supplement this opinion letter if any applicable laws change after the date of this opinion letter or if we become aware after the date of this opinion letter of any facts, whether existing before or arising after the date hereof, that might change the opinions expressed above.

This opinion is furnished in connection with the Final Prospectus Supplements and may not be relied upon for any other purpose without our prior written consent in each instance. Further, no portion of this opinion may be quoted, circulated or referred to in any other document for any other purpose without our prior written consent.

Soluna Holdings, Inc.
April 29, 2022
Page 3

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Company’s Current Report on Form 8-K filed with the Commission on April 29, 2022, incorporated by reference into the Registration Statement, and to the reference to this firm under the caption “Legal Matters” in each Final Prospectus Supplement. In giving such consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder.

Very truly yours,

/s/ Sullivan & Worcester LLP