O-glycosides were synthesized by electrochemical oxidation of phenyl S-glycosides in the presence of primary alcohols in acetonitrile. Similarly, a beta-linked disaccharide was obtained selectively by oxidation of phenyl S-glycoside in the presence of a sugar alcohol. Electrosyntheses were performed under controlled potential or at constant current, in an undivided cell, on a large scale. 1 to 60 g of phenyl S-glycosides in 0.5 to 1 dm3 of acetonitrile were converted with chemical yields in the range of 65-75%.