Abstract: Several metal ions, such as mercury, cadmium, copper, zinc, nickel and cobalt, may be removed from waste waters and similar solutions by treating such solutions with a cation exchanger in the presence of a polyamine. A treatment with clay minerals such as bentonite or montmorillonite in the presence of tetraethylenepentamine is preferred. The solution may be first combined with polyamine and then contacted with the cation exchanger, but in a preferred embodiment, the polyamine and cation exchanger are combined first to form a solid adsorbent and then contacted with the solution.