SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* LOY BERTRAND (Last) (First) (Middle) 2 SETTLEMENT WAY (Street) ACTON MA 01720 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol MYKROLIS CORP [ MYK ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) V.P. & CFO
	3. Date of Earliest Transaction (Month/Day/Year) 05/28/2004
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/28/2004		M		3,437	A	$6.8	8,689(1)	D
Common Stock	05/28/2004		M		3,125	A	$11.6	11,814(1)	D
Common Stock	05/28/2004		M		8,832	A	$15	20,646(1)	D
Common Stock	05/28/2004		S(2)		15,394	A	$16	5,252(1)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (Right to Buy)	$6.8	05/28/2004		M			3,437	(3)	12/19/2009	Common Stock	3,437	(4)	37,813	D
Employee Stock Option (Right to Buy)	$11.6	05/28/2004		M			3,125	09/30/2003	11/29/2008	Common Stock	3,125	(4)	21,875	D
Employee Stock Option (Right to Buy)	$15	05/28/2004		M			8,832	(5)	08/09/2008	Common Stock	8,832	(4)	61,168	D

Explanation of Responses:

1. Included in these shares are an aggregate of 363 shares purchased under the Mykrolis Corporation Amended and Restated 2001 Employee Stock Purchase Plan subsequent to February 17, 2004 (the date of the most recent amended Form 4 on which information concerning common stock was provided in Table 1).

2. All sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 12, 2003.

3. These options vest 25% on December 19, 2003 and thereafter quarterly in 12 equal increments.

4. These options were granted pursuant to an employee stock option plan that provides for the grant of options in consideration of services of an employee.

5. The option vests 25% on 8/9/02 with the balance vesting in equal quarterly installments beginning 11/9/02.

Remarks:

	Bertrand Loy	06/01/2004
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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