Si@SiOx/C nanoporous spheres as anode materials for high-performance lithium ion batteries were fabricated through a facile magnesiothermic reduction of well-ordered mesoporous silica and subsequent impregnating of carbon precursor into the Si@SiOx nanoporous spheres followed by carbonization at 800 degrees C. The obtained nanoporous spheres present an interweaved porous structure composed of high-capacity Si, inactive SiOx and conductive carbon, which can effectively enhance the electrochemical performance of the composite materials. The resulting Si@SiOx/C nanoporous spheres display a reversible specific capacity of 913 mA h g(-1) at the first cycle and the capacity retention ratio is 97% after 60 cycles at a current density of 100 mA g(-1). The nanoporous structure of Si, SiOx and C can effectively accommodate the volume change for Si-based materials' expansion, release the mechanical stress and improve the electronic conductivity. The Si@SiOx/C nanoporous spheres exhibit a great potential as anode materials for lithium ion batteries. (c) 2012 Elsevier B.V. All rights reserved.