The complexation of poly(methacrylic acid) (PMAA) brushes prepared by the "grafting from" technique with silver, calcium, copper, aluminum, and lanthanum ions was studied. XP and IR spectra confirmed the formation of stable complexes. The IR spectra revealed different coordination geometries depending on the nature of the metal ion. The degree of complex formation was strongly dependent on both the metal ion concentration and the graft density of the polymer brush. The degree of dissociation of the PMAA brush and the total amount of calcium adsorbed were quantitatively evaluated.