In order to treat aqueous effluents containing organic pollutants, several techniques can be considered depending on the organic compound concentration. Sonochemistry appears to be a promising solution to answer water remediation issue. In fact, when submitted into a liquid, ultrasound can induce the nucleation, growth, and violent collapse of vapor/gas filled bubbles. However, despite the extreme local conditions observed during acoustic cavitation, using ultrasound alone is efficient only at low concentration in organic pollutants. In the present study, 0.05 M oxalic acid degradation kinetics were followed at 40 degrees C under various conditions, in presence or not of Pt/TiO2 catalyst under silent conditions or ultrasound at 20 and 360 kHz. Experiments were achieved under controlled atmosphere and comparison between argon, Ar/O-2(20vol% O-2) and pure O-2 conditions was performed. Oxidation rate increase of oxalic acid was measured under Ar/O-2 atmosphere in presence of Pt/TiO2 catalyst due to strong dispersion effect of both low and high ultrasonic frequency and formation of chemically active species by sonolysis. High frequency ultrasonic irradiation under Ar/O-2 atmosphere gives the highest kinetic increase compared to silent conditions with oxalic acid degradation rate around 13 mu mol min(-1) at 40 degrees C with 2 g L-1 of 3 wt% Pt on P25 TiO2 catalyst. (C) 2014 Elsevier B.V. All rights reserved.