Epoxidation of 1,4-bis(allyloxy)butane by hydrogen peroxide under phase transfer catalysis and transition metal salts was investigated. The most advantageous conditions for the epoxidation were determined (temperature, reaction time, the type and amount of phase transfer catalyst, molar ratio of hydrogen peroxide to 1,4-bis(allyloxy)butane, the amount and molar ratio of H3PO4:Na(2)WO(4)center dot 2H(2)O). The process was evaluated in terms of the conversion of 1,4-bis(allyloxy)butane, hydrogen peroxide and the yields of monoepoxide and diepoxide. (c) 2005 Elsevier B.V. All rights reserved.