The Bayer-Williger oxidation of cyclic ketones to form esters or optically active lactones is an important transformation in organic synthesis for the production of steroids, pheromones and monomers of biodegradable polymers. The synthesis of δ-valerolactone was carried out using available, stable, safe during storage hydrogen peroxide adducts. Monoperoxophthalates of sodium and magnesium provide high conversion and selectivity of the process under mild conditions, neutralizing the occurrence of side reactions.