A method for preparing magnetic composite particles with a core containing iron oxide encapsulated in crosslinked chitosan (CS) and a functionalized synthetic copolymer shell is proposed and optimized. The magnetic material is produced in situ. Surface vinyl groups are introduced by attaching glycidyl methacrylate (GMA) to the hydroxyl or amino chitosan residues via ether or N-alkyl bonds in acidic medium. These groups are used in a subsequent synthesis step as starting points for free radical copolymerization of GMA, ethylene glycol dimethacrylate (EGDMA) and poly(ethylene glycol methylmethacrylate) (PEG-MMA). The epoxy rings are opened in the final step with ethylenediamine (EDA). The results confirm that a grafted polymer layer has been anchored on the surface by covalent bonds. Sorption batch experiments using copper (II) ion solutions were conducted in order to compare the performance of the synthesized materials as heavy metal adsorbents. The functionalized particles show superior adsorption capacity compared to the ungrafted material. (C) 2012 Elsevier B.V. All rights reserved.