The combustion kinetics of coke laydown on wet oxidation catalysts was studied by means of temperature-programmed oxidation and mass spectrometry within the temperature range (30-600 degreesC). The coke deposits were formed over three different catalysts 1 wt.% Pt/Al2O3, MnO2/CeO2 and 1 wt.% Pt-MnO2/CeO2 during phenol deep oxidation in a three-phase slurry reactor at various reaction conditions (exposure time, temperature, oxygen pressure, catalyst loading). The carbon oxides, oxygen and water fluxes arising from the combustion of the carbonaceous deposits in a 5% O-2/He mixture, were continuously monitored. In all cases, unimodal quasi-Gaussian distributions were obtained for CO2 while no CO was detected. These evolutions were successfully described by a modified "fractal power-law" grain model. The coke-dependence of the carbon dioxide profiles was related to the fractal dimension of the catalyst surface and to the oxygen partial order during coke burn-off. The corresponding change in O-2 partial order was ascribed to competition between three steps in the combustion mechanism: non-dissociative O-2 chemisorption, interaction of oxygen with undissociated dioxygen bearing surface species, physical desorption of the complex oxide as carbon dioxide. (C) 2001 Elsevier Science B.V. All rights.