A bacterial strain that produced extracellular phytase was isolated from soil near the roots of the leguminous plants and identified to be a genus of Enterobacter Enterobacter sp. 4. The optimum condition for phytase production in PSM medium was pH of 5.5 and 3 days of cultivation at 37 degrees C. When localization of phytase activity of Enterobacter sp. 4. was determined, 81.7% of the enzyme activity was found in the extracellular fraction, 4.4% of the activity was detected in the periplasmic space, and the remaining activity was in the intracellular and cell-bound fraction. The maximal phytase activity was observed at pH 7.0-7.5 and it was most stable at pH 6.0-8.0. The optimum temperature of this enzyme activity was 50 degrees C, bill enzyme activity was gradually lost at temperature above 60 degrees C. The crude enzyme was inhibited by each addition of 1 mM Zn+2, Ba+2, Cu+2, Al+3, and ethylenediaminetetraacetic acid (EDTA).