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                                  EXHIBIT 10.28

             Supplemental Executive Retirement Plan for Key Salaried
                        Employees of Mykrolis Corporation

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                     SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN
                          FOR KEY SALARIED EMPLOYEES OF
                              MYKROLIS CORPORATION

INTRODUCTION

Mykrolis Corporation hereby establishes the Supplemental Executive Retirement
Plan for Key Salaried Employees of Mykrolis Corporation effective as of the
Effective Date for the following purposes:

(1)  To provide benefits to certain key salaried employees based on compensation
     which is not included in the definition of compensation under the terms of
     the Mykrolis Corporation Savings and Investment Plan due to the deferral of
     such compensation under the terms of this Supplemental Plan or under any
     other nonqualified deferred compensation plan of Mykrolis Corporation. Such
     benefits shall be equal to the benefits which would have been provided
     under the terms of the Savings Plan if such deferred compensation were
     included in the definition of compensation under those plans and if the
     limitations of Sections 401(a)(17), 402(g), and 415 of the Code, and the
     non-discrimination requirements of Code Sections 401(k) and 401(m) did not
     apply.

                              SECTION 1 DEFINITIONS

The following terms when used in this supplemental plan with initial capital
letters shall have the meanings assigned to them below. Except where the context
otherwise requires, words imparting the singular number shall include the plural
number and vice versa, words denoting any gender shall include all genders and
words denoting persons shall include bodies corporate and vice versa:

1.1.     "Administrative Committee" means the committee established pursuant to
         Section 5.4 below to administer the Supplemental Plan.

1.2.     "Board" means the Board of Directors of Mykrolis Corporation, as from
         time to time in office.

1.3.     "Code" means the Internal Revenue Code of 1986, as amended from time to
         time. Reference to any section or subsection of the Code includes
         reference to any comparable or succeeding provisions of any legislation
         which amends, supplements or replaces such section or subsection.

1.4.     "Company" means Mykrolis Corporation, a Delaware corporation, together
         with any subsidiary or affiliated corporation that the Board determines
         to add to this Supplemental Plan.

1.5.     "Effective Date" means April 1, 2001, subject to the approval of the
         Board of Directors of Mykrolis Corporation, which approval may be given
         before or after the Effective Date.

1.6.     "Participant" a key salaried employee of the Company designated by the
         Board to receive benefits under this Supplemental Plan.

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1.7. "Savings Plan" means the Mykrolis Corporation Savings and Investment Plan,
     as it may be amended or restated, from time to time.

1.8. "Supplemental Account" means, for each Participant, the account under this
     Supplemental Plan to which contributions hereunder shall be credited in
     accordance with the provisions hereof. In the discretion of the
     Administrative Committee Supplemental Accounts may be subdivided for
     supplemental employer contributions under Section 2.1, supplemental
     Participant contributions under Section 2.2 and supplemental employer
     matching contributions under Section 2.3.

1.9. "Supplemental Plan" means this Supplemental Executive Retirement Plan for
     Key Salaried Employees of Mykrolis Corporation as set forth herein and all
     amendments hereto.

                  SECTION 2. SUPPLEMENTAL SAVINGS PLAN BENEFITS

2.1. Supplemental Employer Contributions. If contributions to the Savings Plan
     on behalf of a Participant are limited by the application of the limits
     described in Code Sections 401(a)(17) and 415 and/or a Participant makes
     compensation deferrals pursuant to this Supplemental Plan or to any other
     nonqualified deferred compensation plan of the Company, the Company shall
     credit to the Participant's Supplemental Plan Account an amount equal to
     the excess of (a) over (b), where (a) is the amount which would have been
     contributed to the Savings Plan in the absence of the limits described in
     Code Sections 401(a)(17) and 415 and any compensation deferrals under this
     Supplemental Plan or any other nonqualified deferred compensation plan of
     the Company, and (b) is the amount actually contributed under the Savings
     Plan.

2.2. Supplemental Participant Contributions. If a Participant's contributions
     are limited by the limits of Section 415 of the Code or by the annual
     contribution limit under Section 402(g) of the Code, the Participant may
     elect to defer a portion of his gross compensation (prior to any deferrals
     under the Savings Plan, this Supplemental Plan, or any other nonqualified
     deferred compensation plan of the Company) equal to the excess of (a) over
     (b), where (a) is the amount the Participant would have contributed under
     the Savings Plan in the absence of the limitations of Code Section
     401(a)(17), Section 402(g), and Section 415, and/or the non-discrimination
     requirements of Code Section 401(k) and by taking into account the
     Participant's gross compensation (prior to any compensation deferrals
     described above) and (b) is the amount actually contributed by the
     Participant under the Savings Plan.

2.3. Supplemental Employer Matching Contributions. If a Participant makes
     supplemental Participant contributions pursuant to Section 2.2 of this
     Supplemental Plan, the Company shall credit to his Supplemental Account an
     amount equal to the employer matching contributions which would have been
     made pursuant to the Savings Plan if the Participant's supplemental
     Participant contributions had been

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     made pursuant to the Savings Plan, without regard to the nondiscrimination
     requirements of Code Section 401(m).

All payments of benefits to Participants and/or their designated beneficiaries
under this Section 2 of the Supplemental Plan shall be made in any of the three
forms set forth below; the particular form to be selected by the Administrative
Committee in its sole discretion after giving due consideration to the desires
of the Participant and/or his or her designated beneficiary, communicated to the
Administrative Committee at least six (6) months prior to the date on which any
such benefit payment is to commence:

                               A lump sum payment;

                         The payment of a life annuity;

In five, ten or fifteen equal annual installments. (Equal shall mean dividing
the account balance by the number of years remaining before making the annual
installment then due).

Any unpaid balance shall remain in the Participant's Supplemental Account and
shall be adjusted in the manner as provided for in Section 2.

                                    SECTION 3
                              INVESTMENT DIRECTION

Participants shall be entitled to designate what percentage of all contributions
credited to the Participant's Supplemental Account in accordance with Section 2
above will be invested in the various Investment Options (as defined under
Section 1.27 of the Savings Plan) in accordance with the provisions of the
Savings Plan. Participant designations under the Savings Plan shall be effective
for and shall govern the investment of contributions under this Supplemental
Plan; no separate investment designations under this Supplemental Plan shall be
permitted.

                                    SECTION 4
                             DISTRIBUTIONS AND LOANS

4.1. General. Distributions on account of retirement, death, disability or other
     termination of employment under the Supplemental Plan shall be made in
     accordance with Section 2.

4.2. Distributions While Employed. No distributions may be made to a Participant
     under the terms of this Supplemental Plan while the Participant is an
     employee of the Company or of any affiliate or subsidiary of the Company.

4.3. Right of Offset. If, at the time of payment hereunder, the Administrative
     Committee determines that the Participant to whom or on whose behalf
     payment is being made, for any reason, is indebted to the Company or to any
     affiliate or subsidiary of the Company, the Administrative Committee shall
     be entitled to

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     offset such indebtedness, including any interest accruing thereon, against
     any payments otherwise due under the Supplemental Plan.

4.4. Withholding. The Company shall be entitled to withhold from payments due
     under the Supplemental Plan any and all taxes of any nature required by any
     government to be withheld from compensation paid to Participants.

4.5. Loans. No loans to Participants shall be permitted under the Supplemental
     Plan.

                                    SECTION 5
                                     VESTING

A Participant shall be vested at all times in his or her Supplemental Plan
benefits to the same extent that the Participant is vested in his or her
Employer Contributions Accounts under the Savings Plan.

                                    SECTION 6
                                  MISCELLANEOUS

5.1. Amendment and Termination.

     (1)  The Board may at any time and from time to time, amend or terminate
          this Supplemental Plan, without the consent of any Participant or
          beneficiary, provided that no such amendment or termination shall
          reduce any benefits accrued under the terms of this Supplemental Plan
          prior to the date of termination or amendment.

     (2)  Any amendment or termination of the Supplemental Plan shall become
          effective as to a Participant or beneficiary on the first day of the
          month following the effective date of the amendment or termination.

5.2. No Contract of Employment. The establishment of the Supplemental Plan or
     any modification thereof shall not give any Participant or other person the
     right to remain in the service of the Company or of any subsidiary or
     affiliate of the Company, and all Participants and other persons shall
     remain subject to discharge to the same extent as if the Supplemental Plan
     had never been adopted.

5.3. Tax Effects. None of the Company, the Board, the Administrative Committee,
     and any firm, person, or corporation, represents or guarantees that any
     particular federal, state or local tax consequences will occur as a result
     of any Participant's participation in this Supplemental Plan. Each
     Participant shall consult with his or her own advisors regarding the tax
     consequences of participation in this Supplemental Plan.

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5.4. Administrative Committee. The Supplemental Plan shall be administered by
     the Administrative Committee which shall consist of at least three members
     who shall serve at the pleasure of the Board. The initial members of the
     Administrative Committee are listed on Schedule A attached hereto.

5.5. Entire Agreement; Successors. This Supplemental Plan, including any
     subsequently adopted amendments, shall constitute the entire agreement or
     contract between the Company and any Participant regarding the Supplemental
     Plan. There are no covenants, promises, agreements, conditions or
     understandings, either oral or written, between the Company and any
     Participant relating to the subject matter hereof, other than those set
     forth in this Supplemental Plan. This Supplemental Plan and any amendment
     shall be binding on the parties hereto and their respective heirs
     administrators, trustees, successors and assigns, and on all designated
     beneficiaries of the Participant.

5.6. Severability. If any provision of this Supplemental Plan shall be held or
     deemed to be invalid, inoperative or unenforceable as applied to any
     particular case in any jurisdiction or jurisdictions, because of its
     conflicting with any constitution or statute or rule of law or public
     policy or for any other reason, such circumstances shall not have the
     effect of rendering the provision or provisions in question invalid,
     inoperative or unenforceable in any other jurisdiction or of rendering any
     other provision or provisions herein contained invalid, inoperative or
     unenforceable, but this Supplemental Plan shall be reformed and construed
     in any such jurisdiction or case as if such invalid, inoperative or
     unenforceable provision had been contained herein and such provision
     reformed so that it would be valid, operative and enforceable to the
     maximum extent permitted in such jurisdiction or in such case.

   In Witness Whereof, the Company has caused the Supplemental Plan to be
executed by its duly authorized officer as of the 1/st/ day of April, 2001.

                                         MYKROLIS CORPORATION



                                         By:  /s/ Peter W. Walcott
                                            ------------------------------
                                         Title: Vice President & General Counsel
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                                   Schedule A
                 Initial Members of the Administrative Committee

                                  Robert Crook
                                  Fred Faulkner
                                 Alison McKenzie