Pt and Ru catalysts on mesoporous (MSP) TiO2 and ZrO2 were developed using sonochemical irradiation. The catalysts were characterized by XRD, TEM, HR TEM, EDX, and BET methods. The high homogeneity of the active metal phase was confirmed by electron microscopy. The catalysts were examined for the removal of organic pollutants from model wastewaters using the wet air oxidation (WAO) process of acetic, succinic and p-coumaric acids in an autoclave reactor at 140 and 190 degrees C and 50 bar total air pressure. The high activity and stability of Pt supported on a TiO2 (MSP) catalyst in the removal of succinic and p-coumaric acids, and intermediates of their oxidation was demonstrated. The catalytic performances of Ru/TiO2 (MSP) were similar to those of the catalysts prepared by incipient-wetness impregnation of commercial TiO2 supports. (c) 2005 Elsevier B.V. All rights reserved.