Abstract: The catalytic hydrogenation of CO, C₂H₄, C₂H₂ and C₆H₆ on the intermetallic compound LaNis has been investigated by means of the chro-matographic pulse technique wiih a microreactor. The reaction was also carried out on pure Ni in the same apparatus. The experimental results show(1) The catalytic activity of LaNi5 depends on the character of hydro-genated substances. The catalytic efficiency of LaNi₅ compared with Ni decreases in the order CO>C₂H₄>C₂H₂>C₆H₆, but the activity of LaNi₅ for the hydrogenation of C₆H₆ is lower than that of pure Ni.(2) The catalytic activity of LaNi₅ pretreated at 200℃ in flow hydrogen is higher than that of LaNi₅ without treatment.(3) Methanation reactions of CO on both LaNi₅ and pure Ni are first order and the activation energies are 15.5 Kcal/mole on LaNi₅ and 31 Kcal/ mole on pure Ni, respectively.