ON SEMICONDUCTOR CORP — Director's Dealing 2011

May 9, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: ON SEMICONDUCTOR CORP (ONNN)
CIK: 0001097864
Period of Report: 2011-05-05

Reporting Person: KLOSTERBOER ROBERT A. (SVP & GM, Dig & MxdSig Prd Grp)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-05	Common	S	2989.0000	$11.0000	Disposed	68512.0000	Direct
2011-05-06	Common	A	20650.0000	$11.2400	Acquired	89162.0000	Direct
2011-05-06	Common	F	6693.0000	$11.2400	Disposed	82469.0000	Direct
2011-05-09	Common	M	5000.0000	$10.3200	Acquired	87469.0000	Direct
2011-05-09	Common	S	5000.0000	$11.4704	Disposed	82469.0000	Direct
2011-05-09	Common	S	5000.0000	$11.4704	Disposed	77469.0000	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-05-09	Stock Option (right to buy)	$10.3200	M	5000.0000	Disposed	2012-08-01	Common (5000.0000)	Direct

Footnotes

F1: This transaction was made pursuant to the Reporting Person's existing Rule 10b5-1 plan (i.e. a stock trading plan designed to comply with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended).

F2: This transaction reports the acquisition, effective May 6, 2011 of 20,650 shares of common stock resulting from the attainment of a performance goal under an earlier award of Performance Based Restricted Stock Units ("PBRSU Award") as described in further detail below. The Compensation Committee of the Issuer originally awarded 247,797 PBRSUs to the Reporting Person with an effective grant date of March 2, 2009 subject to the Issuer's 2000 Stock Incentive Plan and a related award agreement. The PBRSU Award vests generally over a three-year (twelve quarter) period but only upon the Issuer achieving certain adjusted non-GAAP earnings before interest, taxes, depreciation and amortization ("EBITDA") base and target performance measurements as set forth in the PBRSU Award agreement.

F3: This disposition transaction represents shares withheld by the Issuer pursuant to the Reporting Person's March 2, 2009 award of Performance Based Restricted Stock Units ("PBRSUs"). On May 6, 2011 certain of these units vested. These shares were withheld to satisfy the Reporting Person's withholding obligations for various taxes and similar items. The Issuer will pay these taxes on behalf of the Reporting Person.

F4: This disposition transaction was executed in multiple trades at prices ranging from $11.47 to $11.4716. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide, upon request, to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.