We report measurement of electron-emission yield under the impact of electrons on BN–SiO 2 . The effect of the temperature on the yield of BN–SiO2 is investigated. It is found that, the electron emission drop significantly when the temperature is increased from 22°c to 400°C. The representativeness of EEY measurements on ceramics at room temperature and that not suffered from the specific environment of a Hall Thruster (elevate temperature, electron and ion bombardment) is thereafter discussed.