The crude extract of phytase from rice bran was prepared by the extraction with 2.0% CaCl₂ solution and partially purified by using of ammonium sulphate (35-80% saturation) followed by the dialysis in distilled water. The specific activity of enzyme was increased by 7.4 and 10.8 folds after ammonium sulphate fractionation and dialysis, respectively comparing with the crude extract.                 Characteristics of the partially purified rice bran phytase was also studied.  The enzyme showed an optimum pH of 5.0 and optimum temperature of 50°C.  Data concerning the rate of thermal inactivation revealed that the enzyme retained about 80% and 30% of its activity when heated for 10 min. at 60 and 70°C, respectively.  The enzyme activity was reduced at high substrate concentrations with an optimum substrate concentration of 3.0 mM sodium phytate.  The K_m value was found to be 1.66x10^-3 M and the V_max was 0.95 µM Pi liberated/min/ml enzyme.                 The enzyme activity was markedly influenced by the presence of some metal salts.  Each of CoCl₂, MnSo₄, CaCl₂ and MgSO₄ showed an activating effect on the enzyme reaction when added at concentrations of 1x10^-4 or 1x10^-3 M.  However, both ZnSO₄ and NiCl₂ caused partial inhibitory effect, while FeSO₄ and CuSO₄ were found to strongly inhibit the enzyme activity.