Electrolysis of 3-arylthiomethyl-γ-cephems possessing various substituents on the arylthio moiety undergo chemoselective and product-selective electrooxidation to give several different products. These include isomeric mixtures of the corresponding methoxylated cephems, a bis[(γ-cephem-3-yl)methyl]disulfide or a 3-dimethoxymethyl-γ-cephem. The selectivity of the oxidation is highly dependent on the nature of the substituents on the arylthio moiety which suggests that both steric and electronic effects play an important role in the electrooxidation of 3-arylthiomethyl-γ-cephems.