The electrocatalytic hydrogenation (ECH) of phenanthrene (1) at Raney nickel electrodes in ethylene glycol-water (96:4 v/v) containing boric acid (0.1 M) and sodium chloride (0.1 M) has been investigated under medium pressure (from 3 to 41 atm) of an inert gas (nitrogen) at 80 and 110 degrees C. Under steady current control (J = 250 mA dm(-2)) at 80 degrees C, pressures of 17-24 atm had an adverse effect on the efficiency of the reaction. Under periodic current control (J = 625-700 mA dm(-2) during t(1) = 1 s and J = 0 during t(2) = 8 s) and under pressure (20.4 atm at 80 degrees C, 41 atm at 110 degrees C), the octahydrophenanthrenes (asymmetric (4) and symmetric (5)) were obtained in high yield (91%), conversion rate (99-100%) and current efficiency (94-96%) after a charge corresponding to 8 F mol(-1) At 110 degrees C and 41 atm, the yield of 4; 5 reached 97% after 10 F mol(-1) with 77% current efficiency.