The distribution coefficients of 20 metal ions in acid sulfate media with a, strong acid type cation exchange resin, Dowex sow-X8, are presented. The ammonium sulfate concentration varied from o. IO to I .o M at a constant concentration of sulfuric acid (0.025 2M). The coefficients of metal ions become significantly lower in acid sulfate media than those in sulfuric acid media, thus allowing many separations to be conducted at lower sulfate concentrations. The distribution coeff+ient ,indicates that differences in distribution coefficients between beryllium and a considerable number of metal ions are large enough for good separation. Results of the separation of beryllium from 23 metal ions are given. The acid sulfate system is, also .suitable for a ,clear-cut separation of uranium (VI), thorium and the ,rare earths in. widely varying proportions, even permitting a carrier-free separation of 23*Th from uranium. z+-15, H.fl"P, Sco,l~, F&7, MO and W'zsla and the rare earths&10 in aqueous sulfuric acid or sulfate solutions are also available. Less information has been published concerning cation ekchange than anion. exchange. Systematic studies on the behavior of uranium (VI) on .Amberlite IR; r20 with organic and mineral, acids, including sulfuric acid, have been described b.y KHOPKAR AND DEMO. .STRELOW has published distribution coefficient data for 23 I