Chitosan has been increasingly studied as an adsorbent for removing heavy metal ions and organic compounds from aqueous solutions. Most of the studies used chitosan in the form of flakes, powder, or hydrogel beads. This research investigates the immobilization of chitosan on other granular materials to overcome the poor mechanical property of chitosan and offers the potential for chitosan to be used as a regenerable adsorbent. Nylon 6,6 and poly(ethylene terephthalate) (PET) granules were partially hydrolyzed under an acidic or alkaline condition to allow chitosan to be coated or immobilized on the granules' surfaces. The surface morphologies of nylon 6,6 or PET granules before and after hydrolysis and those with immobilized chitosan layer were examined by scanning electron microscopy (SEM), and their surface properties were characterized through zeta-potential analysis and X-ray photoelectron spectroscopy. The immobilization of chitosan on nylon 6,6 or PET granules was identified to be through the formation of the salt structure (-NH3+ (...) -OOC-) between the surfaces of hydrolyzed nylon 6,6 or PET granules and the chitosan layer. (C) 2003 Wiley Periodicals, Inc.