The preparation of two novel diaza-crown ether crosslinked chitosan was described. Diazacrown ether chitosan (CTSDC) was synthesized by the reaction of chitosan (CTS) with N,N'-diallyl dibenzo 18-crown-6 crown ether. Diazacrown ether crosslinked chitosan (CCTSDC) was prepared by the crosslinked reaction of CTSDC and epichlorohydrin. Their structures were confirmed with infrared spectra analysis and X-ray diffraction analysis. The adsorption properties of CTSDC and CCTSDC for metal ions were also investigated. The adsorption capacities for metal ions were measured and the selectivity was determined in mixture of several metal ions. At 20 +/- 1 degrees C and pH = 4, the adsorption capacities of CTSDC and CCTSDC for Pd2+ is 248.1 mg g(-1), 215.4 mg g(-1), for Ag+ is 157.8 ing g(-1), 85.1 ing g(-1), respectively. CTSDC and CCTSDC also showed high uptake rates for Pd2+ and Ag+. (c) 2005 Elsevier B.V. All rights reserved.