We developed chitosanase immobilized on amylose-coated magnetic nanoparticles and utilized it to produce chitosan oligosaccharides. The magnetic nanoparticles used consisted of magnetite (Fe3O4) and their surface was coated with amylose. Hydroxyl groups of amylose deposited on the nanoparticles were activated chemically and then used to immobilize the chitosanase via multipoint covalent bonds. Compared to the conventional physical-adsorption method, 1.4-2.0 times the amount of chitosanase was immobilized via multipoint covalent bonding under the same experimental conditions. The immobilized chitosanase was used to produce pentamers and hexamers of chitosan oligosaccharides, which possess beneficial biological activities. In batch hydrolysis of chitosan using the immobilized chitosanase, a high yield of target oligosaccharides (40% of the used chitosan, based on weight) was successfully obtained. The immobilized chitosanase could be recovered and reused repeatedly. (c) 2007 Elsevier Ltd. All rights reserved.