A new successive system for hydrogenation of styrene was constructed using a two-compartment cell separated by a Pd sheet electrode. The sole product in the hydrogenation of styrene was ethylbenzene. The amount of ethylbenzene produced increased linearly with electrolysis time after a certain induction period and the rate of ethylbenzene production depended on the applied current. The current efficiency for the production of ethylbenzene in this system exceeded 93% at an applied current of 10 mA.