Soybean seed hull peroxidase (SBP) is an inexpensive oxidoreductive enzyme and could potentially be used to oxidise/polymerise various organic pollutants present in the industrial and petrochemical wastes. SEP is able to retain its catalytic properties under wide ranges of pH and at elevated temperatures. In this study, a systematic evaluation of the biocatalytic properties of SEP was carried out. The optimal pH fur SEP activity is pH 6.0 and significant activity was observed between 2.2 and 8.0. SEP also showed three times higher activity at an elevated temperature of 80 degreesC and at pH 6.0 when compared to the activity at room temperature. The pH and temperature of the reaction mixture were found to significantly influence the SEP activity. SEP is fairly active in organic solvents. The enzyme exhibited highest activity in the presence of 16.67% (w/v) ethanol followed by acetone, methanol and acetonitrile. The enzyme activity was reduced with an increase in concentration of the organic solvent. SEP also showed maximum activity at different concentrations of acetone using a phosphate buffer, pH 6.0 than with the other pH buffers. Benzene/acetone mixture seems to be another better solvent system for SEP where it showed about 65% of its activity at 16.67% (w/v) concentration. (C) 2001 Elsevier Science B.V. All rights reserved.