The course of epoxidation of 1,4-bis(allyloxy)butane with hydrogen peroxide in the presence of H3PO4/NaWO4 center dot 2H(2)O or heteropolyacids: H3PW12O40 and H3PMo12O40 as the catalysts and the ionic liquids as the phase transfer catalysts (cocatalysts) has been investigated. Imidazolium lactates and salicylates with N-alkyl or alkoxy substitute with different length were used as the cocatalysts. The influence of the kind and amount of catalyst on the yield of 1-allyloxy-4-glycidoloxybutane has been determined. (c) 2006 Elsevier B.V. All rights reserved.