A　novel　binderless　tungsten　carbide　bulk　alloyed　with　Re　was　prepared　for　the　first　time.　The　formation　of　solid　solution　of　Re　in　WC　was　demonstrated　by　detailed　microstructural　and　chemical　analyses.　The　Re　alloyed　WC　has　very　high　indentation　modulus　and　nano-hardness　of　771　GPa　and　36.0　GPa,　respectively,　which　increased　by　38%　and　52%　respectively　as　compared　with　those　of　the　conventional　tungsten　carbide.　The　mechanisms　for　the　hardening　of　the　(W,Re)　C　solid　solution　were　analyzed　by　the　first-principles　calculations.　It　indicated　that　alloying　Re　can　increase　the　charge　density　and　occupy　more　bonding　states　of　WC,　leading　to　strong　chemical　bonds　hence　high　hardness.　The　present　results　show　the　feasibility　of　solid-solution　hardening　for　WC　to　obtain　even　higher　hardness.　It　thus　provides　a　new　approach　to　improve　the　mechanical　properties　of　cement　carbides　by　tailoring　the　composition　and　features　of　the　hard　matrix.