Vacuum ultraviolet VUV radiation studies of pyrolytic Al2O3 films have shown the threshold for electron-hole pair production to be approximately 7.8 eV. The voltage dependence of radiation-induced charging shows a sharp maximum with gate voltage applied during irradiation. This is interpreted as competition between electron-hole pair generation and high-field electron injection from the electrodes. Charge centroid measurements using constant-current photoinjection have shown that the initially injected charge is trapped very near the Si-Al2O3 interface. High-field electron injection experiments using a constant-current technique have shown that the injection threshold is markedly improved with 70 A or more of SiO2 between the Si and Al2O3, but this improvement is obtained at the expense of reduced radiation hardness.