Polyvinyl alcohol (PVA) was used as a hydrogen bond functionalizing agent to modify multi-walled carbon nanotubes (CNTs). Nanoparticles of Fe3O4 Were then formed along the sidewalls of the as-modified CNTs by the chemical coprecipitation of Fe2+ and Fe3+ in the presence of CNTs in an alkaline solution. The structure and electrochemical performance of the Fe3O4/CNTs nanocomposite electrodes have been investigated in detail. Electrochemical tests indicated that at the 145th cycle, the CNTs-66.7wt.% Fe3O4 nanocomposite electrode can deliver a high discharge capacity of 656 mAh g(-1) and stable cyclic retention. The improvement of reversible capacity and cyclic performance of the Fe3O4/CNTs nanocomposite could be attributed to the nanosized Fe3O4 particles and the network of CNTs. (C) 2009 Elsevier Ltd. All rights reserved.