By　selectively　promoting　heterogeneous　nucleation/growth　of　MoS2　on　graphene　monolayer　sheets,　edge　oriented　(EO)　MoS2　nanosheets　with　expanded　interlayer　spacing　(similar　to　9.4　angstrom)　supported　on　reduced　graphene　oxide　(rGO)　sheets　were　successfully　synthesized　through　colloidal　chemistry,　showing　the　promise　in　low-cost　and　large-scale　production.　The　number　and　edge　length　of　MoS2　nanosheets　per　area　of　graphene　sheets　were　tuned　by　controlling　the　reaction　time　in　the　microwave-assisted　solvothermal　reduction　of　ammonium　tetrathiomolybdate　[(NH4)(2)MoS4]　in　dimethylformamide.　The　edge-oriented　and　interlayer-expanded　(EO&IE)　MoS2/rGO　exhibited　significantly　improved　catalytic　activity　toward　hydrogen　evolution　reaction　(HER)　in　terms　of　larger　current　density,　lower　Tafel　slope,　and　lower　charge　transfer　resistance　compared　to　the　corresponding　interlayer-expanded　MoS2　sheets　without　edge-oriented　geometry,　highlighting　the　importance　of　synergistic　effect　between　edge-oriented　geometry　and　interlayer　expansion　on　determining　HER　activity　of　MoS2　nanosheets.　Quantitative　analysis　clearly　shows　the　linear　dependence　of　current　density　on　the　edge　length　of　MoS2　nanosheets.