The Si(111)-7×7 surface has been subjected to oxidation by molecular O2 at 90 K and the kinetics of this process have been studied by x-ray photoelectron spectroscopy (XPS). In the midst of the oxidation process, the thin oxide layer was electronically excited in ultrahigh vacuum using 100 eV electron bombardment. No charging of the oxide layer was observed. It was found that excitation of the oxide layer by electron bombardment led to almost no change in the oxidation kinetics, measured following bombardment. XPS studies showed that two oxygen-containing surface species are produced by oxidation (in the absence of electrons) with O(1s) binding energies of 533.1 and 535.1 eV. Upon electron bombardment, the higher binding energy species is converted to the lower binding energy species. Continued oxidation after electron bombardment showed that the higher binding energy species was replenished again. This result suggests that adsorption at 90 K leads to highly strained Si–O–Si species and that electron bombardment of these species produces the stable oxidized structure. The results are compared to similar experiments on Al2O3 where, in contrast to a SiO2 film, it was found that surface charging of a thin Al2O3 film on Al(111) leads to a greatly enhanced oxidation rate.