To　find　the　changes　of　surface　compositions　during　life　time　of　the　Scandia-doped　impregnated　dispenser　cathodes,　two　cathodes　have　been　tested　at　an　activation　temperature　of　1150　degrees　CB-Mo　and　an　operation　temperature　of　1000　degrees　CB-Mo,　respectively,　in　an　AES　system　up　to　more　than　7,000　hours.　Surface　compositions　were　monitored　in-situ　at　intervals.　The　tested　results　have　been　reported　and　discussed　in　this　paper.