Catalytic wet oxidation reactions of aqueous phenol over unpromoted, base- and noble-metal promoted MnO2/CeO2 catalysts were carried out under mild conditions (80-130 degreesC, 0.5MPa O-2) in a batch slurry reactor. Even though the catalyst-mediated oxidation was very effective in destroying phenol, only a moderate selectivity toward complete mineralization into CO2 and H2O was attained due to parallel formation of deactivating carbonaceous deposits. Promotion of the mixed-oxide catalysts with platinum and/or silver enhanced the mineralization selectivity and reduced appreciably the amount of deposits.