The catalytic decomposition of nitrous oxide to nitrogen and oxygen was studied over Rh/ZnO, Rh/CeO2, Rh/ZSM-5, Cu-ZSM-5 and Co-Al-CO3-HT (hydrotalcite). The effects of metal loading and calcination conditions upon the catalytic performance were examined on Rh/ZnO. A 0.5 wt.% Rh/ZnO catalyst was found to be the most active catalyst, whose reaction rate was 4.0 x 10(4) mu mol(N2O). g(-1). h(-1) under the conditions of 950 ppm N2O and 5% O-2 at 300 degrees C. The oxidized Rh/ZnO showed a higher activity than that calcined in a reducing atmosphere. The TEM and EDX observations revealed the formation of particles of ca. 50 Angstrom in diameter. They consisted of rhodium and zinc oxides as major and minor components, respectively. The activities of all these catalysts decreased when NO2 and H2O were added to the feed.