The present study reports the treatment of municipal solid waste (MSW) derived landfill leachate (initial pH = 7.82 and chemical oxygen demand (COD) = 6400 mg L-1) using catalytic wet oxidation (WO) process. The reaction was performed under moderate conditions (110-150 degrees C temperature and 0.7 MPa total pressures) in the presence of a CuSO4 catalyst. The effect of the promoter (Na2SO3) was also seen on the COD removal. The results were compared with that obtained for Fe2+ and H2O2 combination. Among all tested combinations, (CuSO4 + Na2SO3 + air) exhibited the best performance with similar to 90% COD reduction at 150 degrees C temperature and 0.7 MPa pressures. Under these conditions, the biodegradability of the treated effluent was improved to 0.66 (from an initial value of 0.38). The average oxidation state of carbon (AOSC) value and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of carboxylic acids in the treated effluent.