A highly effective method to synthesise dialkyl peroxides from alkyl hydroperoxides and alkyl bromides in a liquid-liquid-liquid system using tetraalkylammonium salts as phase-transfer catalysts is reported. This process was conducted in the presence of highly concentrated aqueous KOH solutions and cyclohexane as an organic solvent. In a liquid-liquid-liquid system, the phase-transfer catalyst forms an insoluble third-liquid phase between the organic and aqueous phases that enables the catalyst to be recycled multiple times. Dialkyl peroxides were obtained in high yields and with 100% selectivity. (c) 2010 Elsevier B.V. All rights reserved.