Mechanism of NO decomposition over perovskite(-like) oxides was explored through investigating the experiments of O-2-TPD and the activity of NO decomposition. It was found that the mechanism of NO decomposition over perovskite(-like) oxides was performed in a 'recycle' way, in which the recycle of NO2 (its formation and dissociation) plays an important role in the reaction and relates greatly with the activity. Because NO2 dissociation reaction (2NO(2) = 2NO + O-2) is an important step in the process of NO decomposition, catalytic activity of NO decomposition over perovskite(-like) mixed oxides achieved only at high temperatures, at which the NO2 dissociation reaction occurs. (c) 2005 Elsevier B.V. All rights reserved.