Catalytic wet air oxidation of oxalic acid in aqueous solution was investigated in a stirred reactor over a Pt (0.7% in wt)/Al2O3 catalyst at atmospheric pressure, in a concentration range of oxalic acid of 500-3000 ppm, and at a temperature range of 313-353 K. The conversions obtained after 5 h were 28.96 %, 45.98 % and 30.74 % for initial concentrations of 500, 1500, 3000 ppm, respectively. A rate equation of oxalic acid oxidation, in mol.h-1.g-1Pt was determined from measurements of initial rates, at different initial concentrations of oxalic acid, temperatures and catalyst mass loads. The activation energy for oxalic acid conversion was found to be 24.6 kJ mol-1.The heterogeneous catalyzed free-radical oxidation of oxalic acid was discussed.