The electrocatalytic hydrogenation ( ECH) of 2,6- dimethylphenol and 2-tert- butylphenol was performed at RaNi cathodes in aqueous buffers containing various amounts of didodecyldimethylammonium bromide ( DDAB). Without surfactant, 2,6- dimethylcyclohexanol, 2- tert-butylcyclohexanone and 2- tert- butylcyclohexanol were obtained, at 65 degrees C, with very low yields. The surfactant effect on the yields, the selectivity of the reaction and the diastereoisomeric composition of alkylcyclohexanols produced was studied in acidic and basic solutions in relation to the substrate adsorption. At pH 9 the efficiency of the hydrogenation reaction was significantly improved by low amounts of DDAB, which led to an increase of the alkylcyclohexanols formation. In particular, cis- 2- tertbutylcyclohexanol was obtained with a high diastereoselectivity.