Valence band photoemission (XPS), valence band electron energy loss spectroscopy (EELS), Ce3d and 4d XPS, O1s XPS and O1s X-ray absorption (XAS) have been investigated for oxidized and sputtered single crystal CeO 2 films and for oxidized Ce foil. Features were identified that distinguish between the Ce 4 + or Ce 3 + oxidation states. Ce 4 + was identified by the highest binding energy peaks in the Ce4d spectrum at 122.8eV and 126.0eV and lowest energy peak in the O1s XAS spectrum at 530eV. Ce 3 + was identified by the lowest binding energy peak in the Ce4d spectrum at 105.4eV, the Ce4f valence level peak at 2.0eV and excitations in the band gap in EELS. The Ce4d spectra are similar to the Ce3d spectra in that satellite peaks that are related to the final state occupation of the Ce4f level dominate the spectra. The interpretation of the Ce4d spectra is more complicated than that of the Ce3d spectra, however, due to multiplet splitting which has a greater influence in the Ce4d spectra. The O1s XAS are much easier to interpret than XAS spectra from the Ce core levels. The O1s XAS spectra reflect the unoccupied density of states of the cerium oxide without being significantly affected by final state relaxation of the Ce energy levels. The O1s XPS spectra show only a 0.3eV difference in binding energy between Ce 4 + and Ce 3 + in the oxides provided the spectra are corrected for band bending.