March 29, 2019

Justin M. Miller, Esq.
Executive Vice President, General Counsel
Avantor, Inc.
Radnor Corporate Center
Building One, Suite 200
100 Matsonford Road
Radnor, PA 19087

        Re: Avantor, Inc.
            Amendment No. 1 to Registration Statement on Form S-1
            Filed March 15, 2019
            File No. 333-229578

Dear Mr. Miller:

      We have reviewed your amended registration statement 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 by amending your registration statement
and providing the
requested information. 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 registration statement and the
information you
provide in response to these comments, we may have additional comments. Unless
we note
otherwise, our references to prior comments are to comments in our March 7,
2019 letter.

Amendment No. 1 to Registration Statement on Form S-1 filed March 15, 2019

Conflicts of interest, page 9

1.     We note your response to prior comment 3. Please highlight in this
section how the price
       of your common stock could affect the underwriter's holdings of your
preferred stock and
       warrants. Also, please clarify your references to "more than 5%" and
"greater than 10%"
       to more specifically identify the percentages.
 Justin M. Miller, Esq.
FirstName LastNameJustin M. Miller, Esq.
Avantor, Inc.
Comapany2019
March 29, NameAvantor, Inc.
March 29, 2019 Page 2
Page 2
FirstName LastName
We are subject to product liability and other claims in the ordinary course of
business, page 25

2.       Please expand your response to prior comment 6 to tell us whether
products you sell or
         your customers' products incorporating your products have been in the
past subject to
         material litigation.
Management's Discussion and Analysis of Financial Condition and Results of
Operations, page
54

3.       Please clearly disclose the substance of the second sentence of the
third paragraph in your
         response to prior comment 2.
Results of Operations, page 58

4.       Your reference to double-digit growth on page 59 appears to refer to
growth between 10%
         and 99%. Please revise to provide more specific disclosure.
5.       We note your tables that attribute "Baseline VWR" as a "reason for
change" in 2018.
         However, from the information on page 71, it appears that "Baseline
VWR" does not
         reflect the results of the VWR business after the 2017 acquisition and
instead presents
         2018 results based on an assumption that the VWR business' performance
was unchanged
         in 2018. If so, please revise your tables to remove any implication
that "Baseline VWR"
         information reflects actual results of the VWR business during 2018.
In this regard, it is
         unclear why it is appropriate to attribute 2018 "period-over-period
change" to the 2017
         performance of VWR as you mention on page 58 if you do not know how
the VWR
         business performed during the 2018 period; please advise or revise.
Our Products and Services, page 94

6.       Please expand your response to prior comment 22 to tell us whether any
product or service
         class within the categories disclosed in the graphs on page 95
accounted for 10 percent or
         more of your revenue during any of the last three fiscal years.
Principal Stockholders, page 142

7.       We note footnote (5) on page 144. Please also provide the information
required by the
         last sentence of Regulation S-K Item 403(a) and (b).
8.       Please tell us how your disclosure will reflect each conversion
alternative mentioned in
         the last paragraph on page F-32.
Certain Relationships and Related Party Transactions, page 146

9.       We note you identify New Mountain Capital as your sponsor, that
Avantor was acquired
         by affiliates of New Mountain Capital, your disclosure that you
acquired NuSil in 2016,
         and that both NuSil and your predecessor were controlled by New
Mountain Capital.
 Justin M. Miller, Esq.
Avantor, Inc.
March 29, 2019
Page 3
         Please expand your response to prior comment 29 to provide an analysis
supporting your
         conclusion that New Mountain Capital and those with whom new Mountain
Capital acted
         in connection with these transactions are not promoters; it remains
unclear whether all
         disclosure required by Regulation S-K Item 404(c)(1) is included in
your prospectus.
10.      We note your disclosure in note 14 beginning on page F-31. If you will
be redeeming the
         Existing Senior Preferred at their redemption value plus a call
premium, please clarify
         your disclosure in this section. If any call premium creates
additional conflicts of interest
         for any of your underwriters, please add corresponding disclosure in
the appropriate
         locations in your filing.
11.      We note your references throughout this section to "prior
stockholders," "prior award
         holders," "other prior equityholders," and an "individual," etc.
Please ensure that you
         have name each related person and identified the basis on which the
person is a related
         person. Also disclose the amount of each related person's interest in
each transaction
         required to be disclosed by Regulation S-K Item 404.
Stockholders Agreement, page 146

12.      From your revisions in response to prior comment 26, it appears that
many of the
         provisions mentioned in the first and second paragraph of this section
do not terminate in
         connection with this offering. Please describe the operation of those
provisions. Also,
         please disclose which director was designated by each shareholder
under the agreement.
Registration Rights Agreement, page 146

13.      Please expand your revisions in response to prior comment 26 to
disclose the material
         terms of this agreement.
CPECS, page 147

14.      Please disclose the dollar amount of the related person's CPECs that
were converted into
         shares and the number of your shares that the related person held as a
result of the
         conversion.
Related Persons Transaction Policy, page 151

15.    We note your revised disclosure in response to prior comment 29. Please
provide the
       disclosure required by Regulation S-K Item 404(b) regarding your current
policies and
FirstName LastNameJustin M. Miller, Esq. plan to provide the disclosure
addressed by Item
       procedures. Also, tell us whether you
Comapany NameAvantor, Inc.your new written policy before the effective date of
this
       404(b)(1)(ii) regarding
March registration statement.
       29, 2019 Page 3
FirstName LastName
 Justin M. Miller, Esq.
FirstName LastNameJustin M. Miller, Esq.
Avantor, Inc.
Comapany2019
March 29, NameAvantor, Inc.
March 29, 2019 Page 4
Page 4
FirstName LastName
Description of Indebtedness, page 152

16.      Please expand your response to prior comment 30 to tell us the amount
of additional loan
         available to you based on current circumstances, assuming a willing
lender. Also, please
         disclose the substance of the penultimate sentence of your response to
prior comment 30
         to clarify your disclosure in the second paragraph regarding an
uncommitted facility
         which provides for additional or increased commitments.
Exclusive Forum, page 165

17.      We note that your forum selection provision identifies the Court of
Chancery of the State
         of Delaware as the exclusive forum for certain litigation, including
any "derivative
         action." Please disclose whether this provision applies to actions
arising under the
         Securities Act or Exchange Act. In that regard, we note that Section
27 of the Exchange
         Act creates exclusive federal jurisdiction over all suits brought to
enforce any duty or
         liability created by the Exchange Act or the rules and regulations
thereunder, and 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 and
         regulations thereunder. If the provision applies to Securities Act
claims, please also revise
         your prospectus to state that there is uncertainty as to whether a
court would enforce such
         provision, and that stockholders will not be deemed to have waived the
company's
         compliance with the federal securities laws and the rules and
regulations thereunder. If
         this provision does not apply to actions arising under the Securities
Act or Exchange Act,
         please also ensure that the exclusive forum provision in the governing
documents states
         this clearly.
Exhibits

18.      We note that the last paragraph of your response to prior comment 34
addresses only
         named executive officers. Please also address agreements with other
executive officers as
         required by Regulation S-K Item 601(b)(10).
       You may contact Kristin Lochhead at (202) 551-3664 or Brian Cascio,
Accounting
Branch Chief, at (202) 551-3676 if you have questions regarding comments on the
financial
statements and related matters. Please contact Tim Buchmiller at (202) 551-3635
or Russell
Mancuso, Legal Branch Chief, at (202) 551-3617 with any other questions.



                                                                Sincerely,

                                                                Division of
Corporation Finance
                                                                Office of
Electronics and Machinery
cc:      Joseph H. Kaufman, Esq.