UNITED STATES
                                 SECURITIES AND EXCHANGE COMMISSION
                                              WASHINGTON, D.C. 20549


     DIVISION OF
CORPORATION FINANCE


                                                               April 5, 2019

  By E-Mail

  Mario A. Ponce, Esq.
  Simpson Thacher & Bartlett, LLP
  425 Lexington Avenue
  New York, NY 10017

          Re:     Versum Materials, Inc.
                  Schedule 14D-9
                  Filed on March 29, 2019
                  File No. 005-89759

  Dear Mr. Ponce:

         We have reviewed your filing and have the following comments. In some
of our
  comments, we may ask you to provide us with information so we may better
understand your
  disclosure.

         Please respond to this letter within by amending your filing, by
providing the requested
  information, or by advising us when you will provide the requested response.
If you do not
  believe our comments apply to your facts and circumstances or do not believe
an amendment is
  appropriate, please tell us why in your response.

         After reviewing any amendment to your filing and the information you
provide in
  response to these comments, we may have additional comments.

  Schedule 14D-9

  1.      Please file any relevant excerpts from your Schedule 14D-9 as
soliciting materials in
          connection with your current solicitation of proxies.

  Reasons for the Recommendation, page 28

  2.      We note your disclosure that your board believes the Offer Price is
below the price that
          prospective acquirors would be willing to pay for Versum. Revise your
disclosure to
          describe the basis for your disclosure. Also, provide us
supplementally a copy of the
          presentation from your financial advisor referenced in this
disclosure.

  3.      We note your disclosure in the last paragraph of page 28 that you
refer to certain benefits
          expected from the combination with Entegris. Please revise your
disclosure to quantify
          those benefits.
 Mario A. Ponce, Esq.
Simpson Thacher & Bartlett, LLP
April 5, 2019
Page 2

4.     Refer to the disclosure in the first paragraph of page 31 that the
conditions of the offer
       make it easy for Merck to abandon the offer. Revise your disclosure to
clarify that
       Merck's offer is required to comply with all relevant laws and
regulations. Also, with a
       view toward revised disclosure, provide us support for your suggestion
that Merck
       intends to terminate the offer using a pretext.

Rights Agreement, page 44

5.     Please update this section given your recent decision to terminate the
rights
       agreement/plan. In addition, please disseminate this updated disclosure.

Cautionary Statement Regarding Forward-Looking Statements, page 47

6.     We note your reference to Section 27A of the Securities Act of 1933 and
Section 21E of
       the Securities Exchange Act of 1934. Note that the safe harbor
protections for forward-
       looking statements contained in those federal securities laws do not
apply to statements
       made in connection with a tender offer. See Section 21E(b)(2)(C) of the
Securities
       Exchange Act of 1934 and Regulation M-A telephone interpretation M.2
available at
       www.sec.gov in the July 2001 Supplement to the Division of Corporation
Finance's
       Manual of Publicly Available Telephone Interpretations. Please delete
the reference or
       clarify that it is not applicable to the tender offer.

        We remind you that the filing persons are responsible for the accuracy
and adequacy of
their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.

       Please direct any questions to me at (202) 551-3619.

                                                             Sincerely,

                                                             /s/ Daniel F.
Duchovny
                                                             Daniel F. Duchovny
                                                             Special Counsel
                                                             Office of Mergers
and Acquisitions