Organoselenium acetophenones oxidation using enzymatic reactions has been developed and chemoselectivity of phenylacetone monooxygenase (PAMO) with selenium-containing ketones has been explored. We discovered that this biocatalyst prefers selenium oxidation, which leads to selenoxide in excellent conversion, over Baeyer-Villiger oxidation. (C) 2011 Elsevier B.V. All rights reserved.