Low loading catalysts Ru/gamma-Al2O3 and Ru-Ce/gamma-Al2O3 were prepared by thermolysis of Ru-3(CO)(12) on gamma-Al2O3. The catalysts were characterized by XPS, XRD and SEM. Two new Ru species (Ru-A and Ru-B) were detected during the Ru-3(CO)(12) decomposition process due to chemical interaction with the active OH groups on the surface of Al2O3 support, and the reduction of them can lead to more dispersed metallic phases. The sample was completely decomposed at 673 K in H-2, and RuO2 was formed with minor amounts of Ru-0. When the temperature was increased to 773 K to heat the sample, the ratio of Ru-0 to RuO2 increased. However, after the addition of CeO2, only RuO2 was detected on surface. The catalysts exhibited high activities in Catalytic Wet Air Oxidation (CWAO) of different organic compounds at high concentration such as isopropyl alcohol, phenol, acetic acids and N,N-dimethylformamide, which is attributed to the better dispersion of Ru particles and the addition of CeO2 further enhanced number of effectively active sites on the cluster-derived catalyst surface. (C) 2011 Elsevier B. V. All rights reserved.