In　order　for　practical　applications　in　Vacuum　Electron　Devices　(VEDs),　the　robustness　of　Scandia　Doped　Dispenser　(SDD)　cathodes　has　been　widely　concerned.　Machinability,　emission　performance　from　machined　surface,　recovery　of　emission　after　poisoning;　air　exposure　and　ion　bombardment　have,　thereby,　been　studied.　The　investigation　demonstrated　that　the　cathodes　can　be　successfully　machined　by　normal　lathing　to　the　required　diameters　and　curvature　radius.　A　life　test　with　DC　loads　of　up　to　40　A/cm(2)　at　970　degrees　C-b　has　been　completed　more　than　5000　hours　to　date　for　a　cathode　with　machined　surface.　A　full　restoring　of　emission　has　been　proved　after　the　cathodes　were　exposed　to　air　and　reactivated　for　a　short　time.　This　performance　allows　the　cathodes　to　be　pre-heated　before　assembling　into　the　electron　guns.　Poisoning　experiment　evinces　that　in　comparison　with　that　of　a　311-XM　cathode,　which　was　reported　to　be　less　affected　by　gas　poisoning　than　other　M　cathode,　the　poisoning　thresholds　of　residual　gases　for　the　SDD　cathodes　are　more　than　one　order　of　magnitude　higher　at　equivalent　temperatures　but　with　higher　emission　level.　The　emission　and　surface　behaviour,　when　an　activated　cathode　encounters　ion　bombardment　at　its　operating　condition,　has　also　been　investigated　and　discussed.