The secondary electron emission property and microstructure of La2O3-Y2O3-Mo cermet cathode have been studied. It shows that the cathode prepared by Sol Gel doping method has fine microstructure containing rare earth oxide (RE2O3) nanoparticles and uniform distribution of different substances. Auger Electron Spectroscopy (AES) depth profile result shows that an RE2O3 layer about 28 nm in thickness could be formed on the cathode surface, which plays an important role in the emission. Pre-activation of the cathode is favorable for the improvement of emission property. La2O3-Y2O3-Mo cathode pre-activated exhibits good secondary emission property. The secondary emission yield could reach 5.24, about 1.8 times higher than that of original cathode. The enhancement on the conductivity of materials resulting from the pre-activation is favorable for the replenishment and transport of electrons, thus the secondary emission property of the cathode could be improved. (C) 2010 Elsevier B.V. All rights reserved.