1. Original studies have been made on the use of LnNi5 intermetallides as catalysts for propylene hydrogenation. Kinetic measurements have shown these compounds to be highly active and stable in operation. 2. At 20°C, and over the pressure interval from 1 to 60 atm, the sorptional properties of the intermetallides are closely dependent on the nature of the intermetallic matrix and the included rare-earth metal ions. 3. The catalytic activity of the intermetallide in hydrogenation is determined by its hydrogen sorption, the activity being the higher the higher the sorption capacity for hydrogen and the lower the equilibrium pressure in the intermetallide-hydrogen system. 4. It has been shown that there is a certain periodicity in the variation of sorptional and catalytic properties in moving through the series of LnNi5 intermetallides, this being a reflection of the effect of the rare-earth metal on these characteristics.