A　new　diaphragm　electrochemical　system　was　devised　and　tested　for　hydrogenation　of　soybean　oil　under　moderate　processing　temperature　and　atmospheric　pressure.　With　proper　loading　of　the　catalyst　Pd-C,　the　reactor　was　operated　successfully　for　6　h　and　yielded　hydrogenated　soybean　oil　containing　8.62%　TFAs　with　an　IV　of　88.86　g　I-2/100　g　oil　and　an　AV　of　0.7　mg　KOH/g　oil.　The　low　AV　(acid　value)　of　the　hydrogenated　oil,　indicative　of　the　oxidization　tendency　of　the　oil,　is　highly　desirable　from　the　industrial　application　standpoint.　The　low　specific　isomerization　index　was　reached　with　0.4　mol/L　of　formate　ions　at　pH　5.0　under　60　degrees　C　using　a　constant　applied　current　density　(10　mA/cm(2))(.)　The　extent　of　hydrogenation　was　found　to　increase　with　increasing　current　density,　formate　ion　concentration,　reaction　temperature,　catalyst　loading,　and　speed　of　agitation.　It　was　characterized　that　the　extent　of　hydrogenation　under　low　pH　(2.0-5.0)　was　controlled　by　the　regeneration　of　formate　ion,　whereas　under　high　pH　(6.0-10.0)　the　hydrogenation　was　influenced　strongly　by　the　formate　ion　stability.