The acid-catalyzed oxidation of cycloalkanones C5–C8 and C12 with hydrogen peroxide in alcohols was performed, and dicarboxylic acid esters were obtained as the major products in 53–70% yields. In the first step, geminal bishydroperoxides are generated from five-to- seven-membered cyclic ketones. The Baeyer–Villiger reaction is a side process accompanied by the formation of ω-hydroxycarboxylic acid esters.