Calixarene-modified chitosans (CTS-CA-I and CTS-CA-II) were first synthesized by the reaction of chitosan (CTS-NH2) with 1,3-bis-chloroethoxyethoxy-2,4-dihydroxy-p-tert-butylcalix[4]arene (CA-I) or its benzoyl derivative (CA-II). Their structures were characterized by infrared and X-ray diffraction spectroscopy and scanning electron microscopy (SEM). The adsorption of Ni2+, Cd2+ Cu2+, Pd2+, Ag+, and Hg2+ by CTS-CA-I and CTS-CA-II was studied and the thermodynamic parameter of two calix-arene-modified chitosans toward Hg2+ was deduced. The adsorption properties of CTS-CA-I and CTS-CA-II were greatly varied compared with that CTS-NH2, especially with the adsorption capacity toward Ag+ and Hg2+, because of the presence of the calixarene moiety. (C) 2003 Wiley Periodicals, Inc.