A new adsorbent for heavy metal ions, cyschitin, was produced by modifying chitin in THF With L-cysteine in the presence of sulfuric acid as a catalyst. Its structure was confirmed by elemental analysis and FTIR spectra analysis. The adsorption properties of cys-chitin for Cu-II, Cd-II, Pb-II, Zn-II, and Ni-II were investigated. The effect of pH value on adsorption and adsorption kinetics was examined. The results indicate that the cys-chitin has much better adsorption for Cd-II, Pb-II, and Zn-II than chitin itself. The adsorption capacities of cys-chitin for Cd-II, Pb-II, and Zn-II were 214.6, 351.5, and 107.0 mg/g, respectively. It also had good adsorption properties for heavy metal ions. The adsorption capacities were also affected by the acidity of medium. The adsorbed Cd-II, Pb-II could be eluted by diluted nitric acid. (C) 2003 Wiley Periodicals, Inc.