Nd2CuO4, Nd1.6Ba0.4CuO4 and Nd1.8Ce0.2CuO4 were prepared by means of the citric acid complexing method. The catalytic performances of N2O decomposition to N-2 over this series of K2NF4-type cuprates have been evaluated. Techniques such as XRD, XPS, EPR, TPD, pulsing, in situ DRIFT, and FT-Raman as well as chemical analysis were employed to investigate the nature of the active sites and to identify the possible reaction intermediates. A catalytic reaction mechanism has been proposed. The N2O decomposition activities declined in the order of Nd1.8Ce0.2CuO4 > Nd1.6Ba0.4CuO4 > Nd2CuO4 when the reaction temperatures were below 400 degreesC. Above 400 degreesC, Nd1.8Ce0.2CuO4 was inferior to Nd1.6Ba0.4CuO4. The results of chemical analysis and XPS studies revealed that there are (i) Cu2+, Cu3+. and extra oxygen in Nd2CuO4; (ii) Cu2+, Cu+ and extra oxygen in Nd1.8Ce0.2CuO4; and (iii) Cu3+, Cu2+ and oxygen vacancies in Nd1.6Ba0.4CuO4. There are Cu+, Cu2+ Cu3+ and active oxygen species such as O- (O-2(2-)) or O-2(-) in the used catalysts. The results of EPRI in situ DRIFT and Raman studies suggested that during N2O decomposition NO3-, NO2-, N2O22-, NO-, and oxygen species (O-, O-2(2-), and O-2(-)) were generated. The productions of NO and N-2 are competitive. The reaction mechanism includes the redox actions amidst Cu+ double left right arrow Cu2+ Cu3+ and O2- double left right arrow O-(O-2(2-)) double left right arrow O-2(-) double left right arrow O-2. Oxygen Vacancies are important sites for N2O adsorption and oxygen species O-are required for the formation of the crucial intermediate N2O22-.