Removal of phenol by wet air oxidation was conducted with 1 wt.% Pt/Al(2)O(3) and 1 wt.% Pt/CeO(2) catalysts. During the reaction carbonaceous materials were formed and deposited on the catalyst surface, and the materials deactivated the catalysts. XPS analysis showed that the carbonaceous materials on the Pt/Al(2)O(3) catalyst were composed of four different morphologies. As the wet oxidation proceeded, C(2) type and C(3) type carbonaceous materials transformed into C(4) material. In the Pt/CeO(2) catalysts, however, C(4) material was not formed through the reaction. The broad profiles of CO(2) formation from TPO experiment implied that there were at least two types of carbon deposits burning at different temperatures; one on Pt particles, the other Al(2)O(3) and CeO(2). The primarily formed carbonaceous deposit on Pt particles migrated continuously onto the supports. (C) 2010 Elsevier B.V. All rights reserved.