Density functional theory has been employed to investigate the adsorption and the dissociation of an N2O at different sites on perfect and defective Cu2O(1 1 1) surfaces. The calculations are performed on periodic systems using slab model. The Lewis acid site, Cu-CUS, and Lewis base site, O-SUF are considered for adsorption. Adsorption energies and the energies of the dissociation reaction N2O -> N-2 + O(s) at different sites are calculated. The calculations show that adsorption of N2O is more favorable on Cu-CUS adsorption site energetically. Cu-CUS site exhibits a very high activity. The Cu-CUS-N2O reaction is exothermic with a reaction energy of 77.45 kJ mol(- 1) and an activation energy of 88.82 kJ mol(-1), whereas the O-SUF-N2O reaction is endothermic with a reaction energy of 205.21 kJ mol(-1) and an activation energy of 256.19 kJ mol(-1). The calculations for defective surface indicate that O vacancy cannot obviously improve the catalytic activity Of Cu2O. (c) 2007 Elsevier B.V. All rights reserved.