Thermolysin metalloprotein affinity metal chromatography (MAMC) has been shown to be effective for the removal and concentration of lanthanide and actinide ions from aqueous solution. Using solutions of trivalent lanthanide ions of appropriate radii and of Th4+ and UO22+ ions as models, the calcium-binding sites of immobilized thermolysin have shown appreciable potential for the decontamination of actinide-bearing waste solutions. The zinc-binding site of the affixed protein may also be used for the removal and concentration of divalent transition metal ions.