Electrochemical　hydrogenation　is　a　novel,　alternative　process　for　selective　hydrogenation　of　vegetable　oils,　because　of　its　high　extent　of　hydrogenation　and　low　trans-isomer　formation.　Electrochemical　hydrogenation　of　soybean　oil　in　a　diaphragm　reactor　with　a　formate　ion　concentration　of　0.4　mol/l　at　pH　5.0　under　moderate　temperature　conditions　using　a　current　density　of　10　mA/cm　2　was　investigated　to　identify　the　critical　conditions　affecting　the　selective　hydrogenation　reaction　and　the　resulting　fatty　acid　profile.　The　optimum　composition　was　an　oil-to-formate　solution　ratio　of　0.3　(w/w),　2-3　g　EDDAB　in　100　g　soybean　oil,　and　0.8%　Pd-C　catalyst　loading.　The　electrochemical　hydrogenation　reaction　of　soybean　oil　was　described　by　first-order　kinetics,　and　the　kinetic　rate　constants　and　reaction　selectivity　were　determined　accordingly.　Re-use　of　the　Pd-C　catalyst　up　to　five　times　was　found　to　be　acceptable.　A　comprehensive　evaluation　revealed　that　the　most　significant　conditions　affecting　the　extent　of　hydrogenation　and　the　trans　fatty　acids　content　of　final　products　were　operating　temperature,　pH　of　the　formate　solution,　and　catalyst　loading.　©　2010　AOCS.