The new application of acyltransferase, isolated from Mycobacterium smegmatis for the chemo-enzymatic Baeyer-Villiger oxidation of cyclic ketones to lactones was demonstrated. Acyltransferase exhibited high activity, and high stability under harsh reaction conditions, like oxidation with 60% aq. H₂O₂ at 45°C. This paves the way to a novel robust chemo-enzymatic method for lactone synthesis with high yields.