Y2O3-MO cermet cathodes were prepared by mechanical mixing of Y2O3 and Mo powder. The prepared cermet cathode provides a certain secondary emission yield (3.09), about 1.8 times lower than that for the cathode prepared by sol-gel method. It was found that the cathode prepared by sol-gel method had a smaller grain size, which could be attributed to its higher emission property. The energy distributions of primary electrons in the cathodes with different grain sizes have been simulated by Monte Carlo method. Based on the calculation results, the emission models of the cathodes are established and presented. The cathodes with different grain sizes exhibited different ways of emission. Two types of emission, of reflection emission and transmission emission, existed in the cathode with small grain sizes whereas only transmission emission existed in the cathode with large grain sizes. (C) 2009 Elsevier Ltd. All rights reserved.