Chemically activated graphene/porous Si@SiOx (CAG/Si@SiOx) composite has been synthesized via magnesiothemic reduction of mesoporous SiO2 (MCM-48) to porous Si@SiOx and dispersing in the suspension of chemically activated graphene oxide (CAGO) followed by thermal reduction. The porous Si@SiOx particles are well encapsulated in chemically activated graphene (CAG) matrix. The resulting CAG/Si@SiOx composite exhibits a high reversible capacity and excellent cycling stability up to 763 mAh g(-1) at a current density of 100 mA g(-1) after 50 cycles. The porous structure of CAG layer and Si@SiOx is beneficial to accommodate volume expansion of Si during discharge and charge process and the interconnected CAG improves the electronic conductivity of composite. (C) 2014 Elsevier B.V. All rights reserved.