Abstract:  NiAl mixed oxides with Ni/Al atomic ratio of 2.0, 2.7 and 4.1 were prepared by calcining the corresponding NiAl hydrotalcite-like compounds (NiAl-HLc), and applied in N₂O decomposition. The NiAl mixed oxide with Ni/Al atomic ratio of 2.7 was incipiently impregnated by alkali metal (Na, K, Cs) carbonate solution to prepare the promoted NiAl mixed oxide catalysts. The catalysts were characterized by XRD, ICP-AES, FT-IR, BET, H₂-TPR and XPS techniques, and their catalytic activities for N₂O decomposition were tested. The effect of NiAl mixed oxides composition, alkali metal species, and potassium precursors on catalytic activity was investigated. The results show that the catalytic activity of NiAl mixed oxide impregnated by K₂CO₃ solution is much higher than Na₂CO₃ and Cs₂CO₃ modified catalysts; the catalytic activity of NiAl mixed oxides is largely enhanced by the addition of K species from the precursors of K₂CO₃, K₂C₂O₄ and CH₃COOK.