A rapid radiochemical separation of selenium from arsenic, germanium and zinc based on the precipitation of elemental selenium by NaHSO3 is discussed. Yields of 90% and greater are achieved for selenium in 1 to 2 min. The kinetics, separation characteristics of the process and chemical yield of Se and trace contaminants such as Zn, Ge and As were studied using nondispersive X-ray fluorescence techniques.