The catalytic wet air oxidation of pulp and paper mill effluent was studied using CuSO4, perovskite. based oxides, zeolites and bagasse flyash as catalysts at atmospheric pressure using air as the source of oxygen. Among the catalysts studied the activity Of CuSO4 was the best, having a reduction of 36.5 and 68.1% in BOD and COD values respectively. Among the insoluble catalysts, La0.3Ce0.7CoO3 was the best with a marginally lower activity in comparison to CuSO4. The performance of flyash was also closer to CuSO4 and La0.3Ce0.7CoO3. At a higher catalyst concentration of 5 g/L flyash (initial concentration I g/L), the reduction in BOD and COD values of the pulp and paper mill effluent were 48.9 and 77.4% respectively, whereas the BOD/COD value was increased to 0.56, a value much closer to 0.63, which is an indicator for the complete biodegradability of the effluent. The reactivity of the catalyst was found to be a strong function of the pH of the effluent solution, and a pH of 10 was found to be the best.