Electrochemically generated ArS(ArSSAr)(+) was found to be an effective activator for glycosylation of thioglycosides. Efficiency of the reaction strongly depends on the nature of the counter anion, and B(C6F5)(4)(-) was the most effective among those examined. The method was applicable to various glyocosyl donors including thiogalactosides and thiomannosides and various acceptors including those having secondary hydroxy groups.