This paper reports on Si core/C shell nanofibers as an anode material for Li-ion batteries. The Si core/C shell nanofibers are synthesized using co-axial electrospinning of Si nanoparticles in styrene-co-acrylonitrile core solution and poly(acrylonitrile) shell solution combined with subsequent thermal treatments. The microstructure and elemental composition of the nanofibers are systematically examined using FE-SEM, TEM and WAXD for confirmation of the crystalline Si core/turbostratic C shell structure. In situ observation of contact-lithiation of the Si core/C shell nanofibers is carried out to investigate their mechanical durability during the electrochemical reactions. The electrochemical performances of the nanofibers as an anode are characterized by galvanostatic charge-discharge test. Due to simple processing but a well-developed core/shell structure and good electrochemical performance, the Si core/C shell nanofibers fabricated in this study offer the potential to develop enhanced Si/C nanostructured composite anodes. (C) 2012 Elsevier B.V. All rights reserved.