Graphene-based　nanocomposites　have　been　synthesized　and　tested　as　electrode　materials　for　high　power　lithium-ion　batteries.　In　the　synthesis　of　such　nanocomposites,　graphene　is　generally　introduced　by　either　thermally　or　chemically　reduced　graphite　oxide　(GO),　which　has　poorer　electric　conductivity　and　crystallinity　than　mechanically　exfoliated　graphene.　Here,　we　prepare　few-layer　graphene　sheet　(FLGS)　with　high　electric　conductivity,　by　sonicating　expanded　graphite　in　DMF　solvent,　and　develop　a　simple　one-pot　hydrothermal　method　to　fabricate　monodispersed　and　ultrasmall　Co3O4　nanocubes　(about　4　nm　in　size)　on　the　FLGS.　This　composite,　consisting　of　homogeneously　assembled　and　high　crystalline　CO3O4　nanocubes　on　the　FLGS,　has　shown　higher　capacity　and　much　better　cycling　stability　than　counterparts　synthesized　using　GO　as　a　precursor.　The　products　in　different　synthesis　stages　have　been　characterized　by　TEM,　FTIR　and　XPS　to　investigate　the　nanocube　growth　mechanism.　We　find　that　Co(OH)(2)　initially　grew　homogeneously　on　the　graphene　surface,　then　gradually　oxidized　to　form　Co3O4　nanoparticle　seeds,　and　finally　converted　to　Co3O4　nanocubes　with　caboxylated　anion　as　surfactant.　This　work　explores　the　mechanism　of　nanocrystal　growth　and　its　impact　on　electrochemical　properties　to　provide　further　insights　into　the　development　of　nanostructured　electrode　materials　for　high　power　energy　storage.　(C)　2014　Elsevier　B.V.　All　rights　reserved.