Y zeolite- or alumina-supported ruthenium sulfide catalysts were investigated for the hydrogenation of pyridine to piperidine. Their activity was compared with that of commercial NiMo or CoMo alumina-supported catalysts and they were found to be more active than the latter. RuKY exhibited higher intrinsic activities than RuHY and Ru/Al2O3 catalysts. Mechanical mixtures consisting of RuKY and commercial alumina-supported NiMo- or CoMo-based catalysts exhibited synergy for the hydrogenation of pyridine. This phenomenon was not observed for the other supports. This observation is related to the particular ability of highly dispersed ruthenium sulfide for hydrogen activation.