Catalytic wet air oxidation (CWAO) of aqueous solution of phenol was carried out with pure oxygen at 160 degrees C in a stirred batch reactor on platinum supported oxide catalysts (Pt/CeO2c calcined at 650 and 800 degrees C and Pt/CexZr1-xO2 with x = 0.90, 0.75 and 0.50). The catalysts were characterized before (BET, FT-IR spectroscopy, hydrogen chemisorptions, oxygen storage capacity (OSC)) and after reaction (TPO, elementary analysis, GC-MS and DTA-TGA). The results demonstrate a poisoning of the catalysts during CWAO reaction due to the formation of different forms of carbon deposit on the materials: carbonates and polymeric carbon species. This poisoning phenomenon is limited by the introduction of 50% of zirconium into ceria lattice for the catalysts presenting the lowest surface area. Polymeric deposits play a major role in the catalyst deactivation. (C) 2008 Elsevier B.V. All rights reserved.