As filed with the Securities and Exchange Commission on June 5, 2015

Registration No. 333-          

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

SCYNEXIS, Inc.

(Exact name of Registrant as specified in its charter)

3501 C Tricenter Boulevard

Durham, North Carolina 27713

(919) 544-8600

(Address of principal executive offices) (Zip code)

SCYNEXIS, Inc. 2014 Equity Incentive Plan

(Full title of the plan)

Marco Taglietti, M.D.

Chief Executive Officer

SCYNEXIS, Inc.

3501 C Tricenter Boulevard

Durham, North Carolina 27713

(919) 544-8600

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

Copies to:

Matthew B. Hemington

Cooley LLP

3175 Hanover Street

Palo Alto, California 94304

(650) 843-5000

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

CALCULATION OF REGISTRATION FEE

EXPLANATORY NOTE

SCYNEXIS, Inc. (the “Registrant”) is filing this Registration Statement on Form S-8 for the purpose of registering an additional 510,726 shares of its common stock, issuable to eligible persons under the SCYNEXIS, Inc. 2014 Equity Incentive Plan, which common stock is in addition to the shares of common stock previously registered on the following Form S-8s (collectively, the “Prior Form S-8s”):

Pursuant to General Instruction E to Form S-8, the contents of the Prior Form S-8s are incorporated herein by reference and made a part hereof.

PART II

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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 Durham, State of North Carolina, on this 5th day of June, 2015.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoint Marco Taglietti and Charles F. Osborne, and each of them, as his or her true and lawful attorneys-in-fact and agents, each with the full power of substitution, for him or her and in his or her name, place or stead, in any and all capacities, to sign any and all amendments to this Registration Statement (including post-effective amendments), and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange 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 and necessary to be done in and about the premises, as fully 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 their, 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, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

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EXHIBIT INDEX

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