Fe3O4-pyrolytic graphite oxide (Fe3O4-PGO) composite has been prepared by solvothermal reaction at 200 degrees C. The as-prepared Fe3O4-PGO composite displays excellent cycle stability and rate capability with the initial discharge capacity of 1275 mAh g(-1) and capacity retention of 81% after 50 cycles compared with pure Fe3O4. The reasons are as follows: (i) in situ synthesized Fe3O4 firmly anchors onto the exfoliated PGO sheets, and the PGO acts as a conductive agent to provide a fast path for electron transportation; and (ii) the interstitial cluster structure of microsphere-type Fe3O4 in Fe3O4-PGO composite facilitates more better percolation of the electrolyte, more efficient accommodation with the strain and stress of volume change upon cycling and faster Li-ion transfer. (C) 2012 Elsevier Ltd. All rights reserved.