Polycrystalline　rare-earth　hexaboride　(LaxCe1-x)B-6　were　prepared　by　means　of　the　reactive　spark　plasma　sintering　(SPS),　using　mixed　powders　of　GdH2,　NdH2　and　B.　The　crystal　structure,　surface　texture,　mechanical　property,　electrical　resistivity,　and　thermionic　emission　properties　of　the　sintered　samples　were　investigated.　It　is　found　that　all　the　samples　sintered　by　SPS　exhibit　high　density　(＞　96%)　and　high　value　of　Vickers　hardness　(2310　kg/mm(2)),　which　are　much　higher　than　those　made　by　traditional　method.　Thermionic　emission　results　indicate　that　the　maximum　emission　current　density　of　La0.6Ce0.4B6　is　40.7　A/cm(2)　under　the　applied　voltage　of　1　kV　at　1873　K,　which　is　larger　than　that　of　LaB6　and　CeB6.　Thus,　the　mixed　cystal　of　borides　(LaxCe1-x)B-6,　as　a　cathode,　promises　good　prospects　in　application.