The interaction of two polyampholyte systems, poly(1-vinylimidazole-coacrylic acid) and interpolymer complex poly(acrylic acid)/poly(1-vinylimidazole) with copper(II) ions in water, was examined with potentiometry (pH-metry and Cu-selective electrode) and electron spin-resonance spectroscopy. Coordination of Cu2+ with copolymer proceeded by carboxylic groups, whereas the interpolymer system azole units were also involved in the inner sphere of the complex. Synergism between coordination with metal ions and intramolecular hydrogen or ionic bonds was shown. The interpolymer complex was an effective system for binding, extracting, and concentrating copper ions from water. (C) 2003 Wiley Periodicals, Inc.