The formation of N2O in a mixture of NO, CO, H-2, O-2, and N-2 was investigated experimentally in a tubular-flow reactor containing a catalyst. It was found that the reduction of NO is enhanced by the presences of H,. and to a lesser extent CO. and that N2O is formed as a by-product of NH3 decomposition and NO reduction in the presence of H-2. and through NO reduction in the presence of CO. The main product of NH3 oxidation k N-2 in addition to the products of NO and NO, and the rate of conversion for NH3 to N2O is about 10%. The conversion of NO to N2O is higher in the presence of H-2 than in the presence of CO at lower temperature. and there is a range of temperature in which the formation of NO is enhanced in the presence of either H-2 or CO, whereas CO enhances NO production from catalytic NO reduction more than H-2 in a CO H-2, NO/O-2/N-2 gas system. (C) 2004 Elsevier Ltd. All rights reserved.