In this study, chitosan was crosslinked using the complexing agent N-N'-[bis(2-hydroxy-3-formyl-5-methylbenzyl-dimethyl)]-ethylenediamine (H(2)fmbme). The chemical modification was confirmed by Raman spectroscopy and thermo-gravimetric analysis (TGA). The new chelating polymer was used in batch processes to study Cu(II) ion adsorption in aqueous solution. The results showed that adsorption was dependent on the pH of the solution, with a maximum capacity at around pH 6.0. The adsorption kinetics data were best fitted with the pseudo second-order model, which gave a correlation coefficient of 0.999 and a 1.53% deviation between experimental and calculated q(e) values. The adsorption equilibrium data were fitted with the Langmuir isotherm (R = 0.999), which revealed that the maximum capacity for monolayer saturation was 113.6 mg Cu(II) per gram of the new adsorbent material (1.79 mmol/g). (C) 2007 Elsevier Ltd. All rights reserved.