A tannase (E.C. 3.1.1.20) producing fungal strain was isolated from soil and identified as Aspergillus heteromorphus MTCC 8818. Maximum tannase production was achieved on Czapek Dox minimal medium containing 1% tannic acid at a pH of 4.5 and $30^{circ}C$ after 48 h incubation. The crude enzyme was purified by ammonium sulfate precipitation and ion exchange chromatography. Diethylaminoethyl-cellulose column chromatography led to an overall purification of 39.74-fold with a yield of 19.29%. Optimum temperature and pH for tannase activity were $50^{circ}C$ and 5.5 respectively. Metal ions such as $Ca^{2+}$, $Fe^{2+}$, $Cu^{1+}$, and $Cu^{2+}$ increased tannase activity, whereas $Hg^{2+}$, $Na^{1+}$, $K^{1+}$, $Zn^{2+}$, $Ag^{1+}$, $Mg^{2+}$, and $Cd2+$ acted as enzyme inhibitors. Various organic solvents such as isopropanol, isoamyl alcohol, benzene, methanol, ethanol, toluene, and glycerol also inhibited enzyme activity. Among the surfactants and chelators studied, Tween 20, Tween 80, Triton X-100, EDTA, and 1, 10-o-phenanthrolein inhibited tannase activity, whereas sodium lauryl sulfate enhanced tannase activity at 1% (w/v).