High-level quantum chemical calculations have been performed on the decomposition reactions of N2O with cation-stabilized oxygen species (O-, O-2(-), and O-3(-)), which compose a model catalytic cycle where O-2(-) is regenerated. The calculated results show that O- and O-3(-) can be expected to be the most active species in the N2O decomposition process, with activation barriers at the multiconfigurational second-order perturbation level (CASPT2) of 29.5 and 32.5 kcal/mol, respectively. The calculated activation barrier for N2O decomposition through reaction with O-2(-) is 40.8 kcal/mol. Comparison with experiments involving these species on metal-oxide substrates indicates the role of the ionic surface to reduce the barriers.