The sorption equilibria of copper(II) chelates of EDTA (ethylenediaminetetraacetic acid) from an equimolar solution with cross-linked, polyaminated chitosan beads were investigated. The polyamination was done by introducing different molecular weights of water-soluble poly(ethylenimine) (PEI). Experiments were carried out as a function of the pH, concentration of Cu(II) ions, and temperature. It was shown that whether the initial aqueous phase was acidic or basic, it tended to become neutral after sorption. The amount of sorption increased with increasing the initial concentration of Cu(II) ions, temperature, and molecular weight of PEI introduced into the bead. Moreover, the measured equilibrium isotherms could be correlated by a dual sorption model containing the BET equation for a finite number of layers.