A method has been developed for coulometric titration of selenium.The iodine liberated by selenious acid was titrated with electro-generated stannous tin.Potentiometric and amperometric end point detection can be used for determination of the milligram quantities of selenium, with an error of ca.0.1%.The smallest quantity determined was about 1 microgram, for which the amperometric and Cooke's modified potentiometric methods should be used.