Abstract: The sample is melted with potassium hydroxide and extracted with deionized water. In sulfuric aciddiphenyl glycollic aciddiphenyl guanidinepotassium chlorate system, tungsten (W) and molybdenum (Mo) produce polarographic catalytic waves with peak potentials (vsSCE) at -0.76 V and -0.26 V, respectively. The method provides the high sensitivity and wide dynamic linear range (1.0～100.0 ng/mL for W and Mo). The method has been applied to the determination of W and Mo in National Standard Reference Materials and the results are in agreement with certified values with precision of less than 5%RSD