Measurements of the currents leaving thin films of uranium dioxide undergoing a known rate of fission have determined the secondary electron yield due to fission fragments emerging from the films. This yield was found to vary from about 570 to 300 electrons per fragment over a film thickness from 0.1 to 3 microns. The ratio of charge carried by the secondary electrons emitted from the surface to the charge carried by fission fragments was also determined. This ratio varies slowly with film thickness, from 28 for a 0.1‐micron coating to about 21 for a 3‐micron coating. The behavior of the charge ratio and secondary electron yield with coating thickness is in qualitative agreement with theory.