The distribution of UO 22+ and Th4+ in nitric acid media on crypomelane-type hydrous manganese dioxide (CRYMO) has been investigated by batch equilibrations and column break-through techniques. The parameters studied involve the media composition and concentrations of HNO3, NaNO3, UO 22+ and Th4+. It is found that Th4+ is more strongly adsorbed on CRYMO than UO 22+ with sufficient differences for chromatographic separation from each other. Uranium was quantitatively eluted from a CRYMO column with 0.1M HNO3. Th4+ has been recovered by using 1M HNO3 as eluent.