Ring opening reaction of (alpha-epoxyketones in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in methanol solution under microwave and UV irradiations resulted in the formation of alpha-hydroxy-beta-methoxyketones through C-beta-O bond cleavage in excellent yields. Whereas the nature and location of the additional substituent affect the rate of ring opening, microwave irradiation remarkably raised the rate of reactions compared with UV-light. Cyclic voltammetric and conductometric studies supported these experimental results. (C) 2007 Published by Elsevier B.V.