RuO 2 /γ-Al 2 O 3 and RuO 2 –CeO 2 /γ-Al 2 O 3 catalysts, prepared by impregnation of γ-Al 2 O 3 with aqueous solution containing Ru and Ce were used to study the influence of CeO 2 on the structure and activity of RuO 2 /γ-Al 2 O 3 catalyst in catalytic wet air oxidation (CWAO) of phenol. The surface properties of two catalysts were measured by BET, SEM, XRD and XPS. Slight aggregates of Ru particles were observed on the surface of RuO 2 /γ-Al 2 O 3 catalyst, while a better dispersion of Ru particles was detected in the presence of CeO 2 on the surface of RuO 2 /γ-Al 2 O 3 catalyst. The chemical state of Ru and O was investigated. The results show that the addition of CeO 2 affects the chemical state of Ru and O elements and promotes the increase of the chemisorbed oxygen contents on the catalyst surface. Moreover, the removal of phenol with RuO 2 –CeO 2 /γ-Al 2 O 3 catalyst is more complete than with RuO 2 /γ-Al 2 O 3 catalyst.