The adsorption and desorption of Hg(II) ions onto natural and crosslinked chitosan membranes were investigated. Batch adsorption experiments were carried out as function of pH, concentration of Hg(II) ions, type of crosslinking (glutaraldehyde (GLA) or epichlorohydrin (ECH)) and desorbent solution (NaCl (1M) or EDTA (10(-4) M)). Isotherm studies indicated that Hg(II) ions can be effectively removed by chitosan membranes, mainly by the glutaraldehyde-crosslinked chitosan, at pH = 6.0, and can be easily removed by elution with NaCl (1M) solution.