For quantitative metal salt adsorption, poly(1,3-divinylimidazolid-2-one)/silica [poly BVU(cat.)/silica] particles with different polymer contents have been synthesized by a cationic surface polymerization of 1,3-divinylimidazolid-2-one onto silica. Preliminary experiments with the metal ion salts CoCl(2), CoI(2), CuCl(2), and FeCl(3) on poly-BVU(cat.)/silica particles, a radically produced poly-BVU(rad.) resin, and a cationically produced poly-BVU(cat.) resin have been carried in acetone solution to check the suitability of the adsorbents. The adsorption mechanism for Co(2+) and Cu(2+) on poly-BVU(cat.)/silica is in accordance with the Langmuir model for monolayer adsorption as shown by quantitative adsorption measurements by means of UV/vis spectroscopy. An ion pair adsorption mechanism is suggested for CoCl(2), CoI(2), and CuCl(2) on poly-BVU(cat.)/silica because both environments cationically produced poly-BVU and residual silanol groups are required for linking the cation and anion. ESR spectroscopic results of CoCl(2)-, CuCl(2)-, and FeCl(3)-poly-BVU(cat.)/silica hybrid adsorbates show selective adsorption for Co(2+) and Cu(2+). However, two different adsorption sites are indicated for Fe(3+) on poly-BVU(cat.)/silica. Copyright 2001 Academic Press.