Catalytic epoxidation of olefins

A method for the epoxidation of olefins by hydrogen peroxide which comprises reacting in a liquid phase an olefin with an anhydrous solution of hydrogen peroxide in organic solvent, substantially inert with respect to reagents and epoxide formed, said solvent being in a concentration sufficient to maintain a single liquid phase under reaction conditions, at a temperature between about 0.degree. C. and 120.degree. C. in the presence of a catalyst selected from B.sub.2 O.sub.3 or metaboric acid, which is able to act as a catalyst for the reaction or to generate such a catalyst and is able to remove water from the reaction mixture, in an amount from about 0.5 mole to 10 moles per mole of hydrogen peroxide.