The rate constant and activation energy of liquid-phase oxidation, catalyzed by CuSO4 . 5H(2)O, MnO2, and Co2O3, were found for synthesized wastewaters containing 1000 mg dm(-3) phenol and 1500 mg dm(-3) p-chlorophenol, respectively. Among the catalysts, CuSO4 . 5H(2)O was demonstrated to be the most effective in reducing the concentration of phenols in wastewaters. The effects of oxygen flow rates and temperatures on the oxidation efficiency were also discussed. The analysis of total organic carbon on the end products after oxidations showed that the liquid phase contained only 10% of intermediate products. Oxidation at different pH values suggested that phenols could be favourably destroyed in an alkaline medium.