Direct decomposition of nitrous oxide (N2O) on K-doped CO3O4 catalysts was examined. The K-doped CO3O4 catalyst showed a high activity even in the presence of water. In the durability test of the K-doped CO3O4 catalyst, the activity was maintained at least for 12 h. It was found that the activity of the K-doped CO3O4 catalyst strongly depended on the amount of K in the catalyst. In order to reveal the role of the K component on the catalytic activity, the catalyst was characterized by XRD, XPS, TPR and TPD. The results suggested that regeneration of the Co2+ species from the Co3+ species formed by oxidation of Co2+ with the oxygen atoms formed by N2O decomposition was promoted by the addition of K to the CO3O4 catalyst. (c) 2007 Elsevier B.V. All rights reserved.