In this work, vanillin-modified thin chitosan membranes were utilized as adsorbents for the removal of Cu(II) from aqueous solutions. A rise of temperature accelerates mass transfer of Cu(II) to the membranes surfaces. The kinetic data did present a rough fit to the traditional Lagergren adsorption kinetic equations. An alternative Avrami kinetic equation was successfully fitted to the kinetic adsorption quantities. From this new equation, from one to three regions presenting distinct kinetic parameters were found, and the use of the parameter n was also related to the determination of the kinetic orders. Variations of the adsorption rate in relation to the contact time and the temperature were also calculated and are discussed. (c) 2004 Elsevier Inc. All rights reserved.