The properties of water-soluble metal-polymers to retain As(III) from aqueous solution are investigated. Poly(acrylic acid)s with different tin contents are prepared. Amounts of 3, 5, 10, and 20 wt% of tin are added to the polymer. The metal compositions are evaluated by thermogravimetry (TG-DSC) and atomic absorption spectroscopy. Structural properties are analyzed by infrared and H-1 nuclear magnetic resonance spectroscopy, and X-ray diffraction. Additionally, specific surface area was measured using CO2 as adsorbate. Arsenic retention properties are studied using the liquid-phase polymer-based retention (LPR) technique. The polymers can bind arsenic species from an aqueous solution in the pH range 4-8. The studies show that the retention capacity is a function of tin content and polymer concentration. At pH 8, the following mol ratios poly(AA)-Sn : As(III) are analyzed: 600: 1, 400 : 1, 200 : 1, 100: 1, and 20: 1. The highest retention, 80%, is obtained with poly(AA)-Sn at 10 and 20 wt % of tin at mole ratios 400: 1, and at nearly to 20: 1. or 40: 1 Sn-As(III). The highest retention is observed at pH 8 and 4. (c) 2007 Wiley Periodicals, Inc.