The addition reactions of diaryl disulfides (ArSSAr) to alkenes and alkynes were achieved with a catalytic amount of an arylbis(arylthio)sulfonium ion (ArS(ArSSAr)(+)), which was generated and accumulated by low-temperature electrolysis of ArSSAr, to give the corresponding diarylthiolated products. The electrolysis of a mixture of ArSSAr and an alkene with a catalytic amount of electricity was also effective to drive the reactions. A cation chain mechanism mediated by ArS(ArSSAr)(+) as a chain carrier is suggested.