The swelling kinetics and equilibrium swelling degree of a series of nickel-containing chitosan cross-linked with glutaraldehyde at amino:aldehyde reactant ratios of 1:0.05, 1:0.17, and 1:0.5 were studied. At an amino:aldehyde reactant ratio of 1:0.17 the crosslinked chitosan was shown to swell in the basic solvent (50 mM tris-HCl, 0.2 M NaCl, pH=7.5) and to have the best nickel retaining properties. Based on these results, the nickel-containing cross-linked chitosan has been concluded to be a potentially good candidate for the specific binding of proteins having terminal histidines.