The separation of elements by means of thiooxine is reviewed. The extraction ranges of the thiooxinates of manganese, iron, cobalt, copper, zinc and mercury, for metal contents of 10−7–10−9g, were determined using the radioactive tracer method. Solubility values in chloroform and distribution coefficients in the system chloroform-water were determined for mercury, zinc and iron thiooxinates. Polytetrafluoroethylene powder was used to eliminate chloroform traces from the aqueous phase.