Scandia　doped　pressed　cathode　was　prepared　by　a　new　method　of　spray　drying　combined　with　two-step　hydrogen　reduction　process.　The　Sc2O3　and　barium-calcium　aluminate　co-doped　powders　have　sub-micrometer　size　in　the　range　of　0.1-1　mu　m　and　scandium　oxide　and　barium-calcium　aluminate　are　distributed　evenly　in　the　powders.　The　cathodes　sintered　by　powder　metallurgy　at　1600　degrees　C-b　have　a　smooth　surface　and　sub-micrometer　grain　structure　with　homogeneous　distribution　of　scandium,　barium,　calcium　and　aluminum　which　are　dispersed　over　and　among　the　tungsten　grains.　This　cathode　has　good　emission,　e.　g.,　the　current　density　of　this　cathode　reaches　31.50　A/cm(2)　at　850　degrees　C-b.　After　proper　activation,　the　cathode　surface　is　covered　by　a　Ba-Sc-O　active　substances　layer　with　a　preferable　atomic　ratio,　leading　to　its　good　emission　property.　The　evaporation　activation　energy　of　SDP　cathode　with　4.58　eV　is　the　highest　among　the　Ba-W,　M-type　and　SDP　cathodes,　and　the　average　evaporation　velocity　nu(t)　of　SDP　cathode　with　1.28　x　10(-8)　g　cm(-2)　s(-1)　at　1150　degrees　C-b　is　the　lowest　one.　(C)　2011　Elsevier　B.　V.　All　rights　reserved.