Catalysts (A) CuO/g-Al2O3, and zeolite-supported (B) CuO/ ZSM-5 (Si/Al = 35) and (C) Cu/ZSM-5 (Si/Al = 70) were used in studies of nitrous oxide decomposition to oxygen and nitrogen. The flow rate of oxygen contained 5% by vol. of nitrous oxide was 200 L(S.T.P.)/h. At 600degreesC, the A, B and C catalysts converted 18, 38% and 86% of nitrous oxide, respectively. The activity of each remained unchanged in 15 h. The Cu/ZSM-5 catalyst (D) from extrusions was mechanically much stronger than that obtained from powder (C).