A simple strategy for the one-step synthesis of AgCl/polypyrrole core/shell nanostructures with controllable shell thickness in the presence of chitosan and thus hollow polypyrrole nanoparticles was reported. AgCl, as a template, was formed during the initial polymerization by the interaction between metal cations and oxidizing anions and adsorbed with chitosan whereupon to induce the coating of polypyrrole layers. TEM, FTIR, XRD demonstrated the formation of the core/shell structure. Possible mechanism was proposed for the formation of core/shell structure and thus hollow particles. (c) 2005 Elsevier Ltd. All rights reserved.