Studies in the hydrogenation of natural oils with catalysts of the platinum metals group have been limited mainly to platinum and palladium with only scant attention to rhodium, ruthenium, iridium and osmium. This preference was dictated largely by economics, palladium being the only noble metal catalyst truly competitive on a usecoat basis with nickel in the hydrogenation of low-priced oils. This paper discusses the noble metal catalysts as a group, points out similarities and differences among the metals relevant to the hydrogenation of natural oils, and describes some of the practical applications of catalysis by palladium.