In this paper a new electrocatalytic hydrogenation process is reported based on the use of LaNi5 electrodes. The charge/discharge of hydrogen within the intermetallic compound through cyclic voltammetry experiments was observed using a powder microelectrode in classical aqueous KOH medium, as well as in other buffered aqueous or hydro-organic media. Most voltammograms are modified in the presence of unsaturated compounds, which indicates that a hydrogenation reaction occurs. Electrocatalytic hydrogenation on a preparative scale was carried out with three unsaturated compounds taken as models (methyl vinyl ketone, 1-decene, 5-hexen-2-one) and it was found that only the C=C bond is hydrogenated with Faradaic efficiencies up to 100%.