The effects of water-soluble polymers on the concentration and separation of the aqueous solutions of the metal ions have been studied. The separation of metal ions can be possible by ultrafiltration-complexation process. The effect of Dextran, which is a water-soluble polymer, on the concentration and separation of metal ions (Cu2+, Ni2+, Fe3+) have been investigated by using EC-PEG 4000 alloy membranes. The permeability of these membranes for metal ions has been recorded at constant pressure but different pH values. It has been noticed that the highest water-permeable membrane is also permeable towards Cu2+ and Ni2+ I but has shown a considerable retention for Fe3+ as a result of the hydrolysis of Fe3+ The retentions of metallic ions and metallic-ion-Dextran couples have been determined at constant pressure but different pH and polymer concentration values. It has been shown that Fe3+/Ni2+ and Fe3+/Cu2+ couples can be separated by using Dextran.