A　single-layer　graphene-CdS　quantum　dot　nanocomposite　is　synthesized　by　a　one-step　reaction　from　graphene　oxide,　and　thus　avoids　the　low-yield　production　and　the　aggregation　of　single-layer　graphene　sheets.　This　new　graphene-based　material　shows　promising　optoelectronic　properties.　Picosecond　ultrafast　electron　transfer　from　the　US　quantum　dots　to　the　graphene　sheets　has　been　observed　by　time-resolved　fluorescence　spectroscopy.