The specific and accurate determination of selenium in human hair can be effected using catalytic polarography in a medium of Na2SO3- KNO3. Sample recovery ranges from 97% to 104%. The selection of experimental conditions and factors that affect the determination were studied in detail. The results show that the medium acidity doesn't have much influence on the measurement, so that the process of sample digestion is simplified. The buffer NH3- NH4C1 improves the stability of analyte and high reproducibility is obtained. The catalytic process and mechanism are also presented in this paper.