The recently discovered cyclohexanone monooxygenase from Thermocrispum municipale (TmCHMO) was employed in the preparation of different optically active sulfoxides. This novel Baeyer-Villiger monooxygenase (BVMO) shows a similar substrate specificity and selectivity when compared with the prototype CHMO from Acinetobacter calcoaceticus. Interestingly, TmCHMO is able to catalyse the asymmetric sulfoxidations at relatively high temperatures, substrate concentrations and in the presence of organic solvents while maintaining or even increasing its selectivity. This shows that this newly found biocatalyst is a promising catalyst for the synthesis of optically active sulfoxides.