Tannase (tannin acyl hydrolase EC 3.1.1.20) produced by Aspergillus awamori nakazawa was purified and characterized. Optimal conditions of production were determined using varying substrate combinations and studying fermentation on various media combinations. Fermentation was carried out for 46 h for optimum enzyme production. Enzyme samples were obtained from the broth after fermentation by acetone precipitation of the supernatant followed by gel filtration chromatography. The properties of the enzyme were investigated. The optimum conditions of temperature and pH were investigated and the effects of urea, surfactant and chelator were studied. Tarmase from this new isolate exhibited optimum activity at 35 degrees C and at a pH of 5.0. Urea concentrations higher than 3 M were inhibitory. Increasing concentrations of sodium lauryl sulphate also led to decrease in activity. Two percent SLS was inhibitory. Increasing concentrations of EDTA had an inhibitory effect on tannase. Tannase was found to be a glycoprotein. Circular dichroism analysis of purified fractions of tannase indicates that the beta-sheet structure in tannase is predominant indicating its globular nature. (c) 2005 Published by Elsevier Ltd.