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.