Measurements have been made of the energy distribution of electrons penetrating thin samples of Al2O3. The observations were made using a 127° electrostatic analyzer. These results allow a determination of the dissipation of electron energy with depth when 2.5–10 kev electrons strike Al2O3. Results obtained indicate that for a given bombarding energy the average energy loss per unit thicknessdW/dxremains almost constant over the entire penetration depth. However,dW/dxdecreases slowly as the bombarding electron energy increases. These observations are in general agreement with those made by Ehrenberg and Franks for 10–40 kev electrons striking phosphors.