The adsorption of metal ions (Mo6+, Cu2+, Fe2+, and Fe3+) was examined on chemically modified chitosans with a hi her fatty acid glycidyl (CGCs), and the adsorption of Cu2+ was examined on ethylenediamine tetraacetic acid dianhydride modified CGCs (EDTA-CGCs) synthesized by the reaction of the CGCs with ethylenediamine tetraacetic acid dianhydride. The adsorption of phosphate ions onto the resulting substrate/metal-ion complex was measured. Mo6+ depicted remarkable adsorption toward the CGCs, although all the Mo6+ was desorbed under the adsorption conditions of the phosphate ions. The other metal ions were adsorbed to some extent on CGCs by chelating to the amino group in the substrate, except for CGC-1, which had the highest degree of substitution (83.9%). Considerable amounts of Fe2+ were adsorbed onto CGCs; however, only a limited number of phosphate ions was adsorbed onto the substrate/metal-ion complex. As a result, the following adsorbent/metal-ion complexes gave higher adsorption ability toward phosphate ions: CGC-4/CU2+, CGC-4/Fe3+, and EDTA-CGC-3/Fe3+. Where, CGC-3 is a chemically modified chitosan with the degree of substitution of 26.5 percentage, and CGC-4 is one with the degree of substitution of 16.0 percentage. (c) 2007 Wiley Periodicals, Inc.