The potential of different Aspergillus strains in carrying out the biotransformation of cyclic ketones was investigated. All the strains employed showed alcohol dehydrogenase and Baeyer-Villiger monooxygenase activities. trans-2-Methylcyclohexanol and trans-4-methylcyclohexanol were prepared in a single isomeric form by the use of Aspergillus terreus SSP 1498 and the corresponding ketones. Baeyer-Villiger oxidation of cyclic ketones by all the fungi Aspergillus led to chiral lactones in good enantio selectivity. (c) 2005 Elsevier Inc. All rights reserved.