Mushroom tyrosinase (polyphenol oxidase, EC 1.14.18.1) was investigated as an alternative to peroxidase enzymes for the catalytic removal of phenolic compounds from wastewaters. Maximum catalytic activity was observed at pH 7 and more than 50% of optimum activity was observed at pHs ranging between 5 and 8. Tyrosinase was unstable under acidic conditions and at elevated temperatures. The activation energy for thermal inactivation of tyrosinase at pH 7 was determined to be 1.85 kJ mol(-1) using L-tyrosine as a substrate. Phenol was successfully transformed by tyrosinase over wide ranges of pH 5-8 and initial phenol concentration (0.5-10 mM, 47-940 mg/l). Several chlorinated phenols were also successfully transformed. Polyethylene glycol and chitosan did not protect tyrosinase from inactivation during the treatment of phenol; however, chitosan induced the precipitation of reaction products arising from phenol transformation.