Abstract: On the basis of gas chromatographic experimental results we here report the hydrogenation reactions of COand CO₂ which took place when Ni (Ⅱ), Co (Ⅱ) oxalato coordination compounds decomposed in hydrogen. The catalytic activity of solid products of thermal decomposition of CoC₂O₄ and NiC₂O₄ was determined by the hydrogenation of CO₂,which decreased rapidly because of the sintering of the metal catalysts. Some decomposition products, such as K₂Oand K₂CO₃, could disperse metal Co or Ni and prevent the metal catalysts from aggregating. For CoC₂O₄/Al₂O₃ and K₂CCo(C₂O₄)₂]/Al₂O₃, the metal-support interaction made it difficult to reduce Co(Ⅱ) and their decomposition curves were somewhat similar to that of Al₂(C₂O₄)₃ at lower temperatures. The infrared spectrum of K₂[Co(C₂O₄)₂]/Al₂O₃ implied that a surface coordination compound was formed.