The radioisotope Mo-99 is the only parent unclide of Tc-99m, an extremely useful tool for medical diagnosis because it has good nuclear properties; its short half life (6.02 hours) and low gamma energy (140Kev). And Tc-99m is used in greater than 80% of nuclear medicine applications. Benzoin oxime precipitation process is one of various processes for separation & purification of fission ⁹⁹Mo. In this study, the recovery yield of Mo and charateristics of precipitation reaction were investigated to obtain optimum operating condition and process design data. In the results of experiments, recovery yield Mo was reached above 96% in condition of 20 B.O./Mo weight ratio and 1N free acidity of Mo solution.