Aluminovanadate oxide, "V - Al - O", has been studied by X- ray photoelectron spectroscopy ( XPS) with the emphasis to reveal chemical modi. cations as a function of the X- irradiation time. Considerable damage was found for V - Al - O and less so for vanadium pentoxide, V2O5, and sapphire, alpha- Al2O3, both serving as reference samples. Modi. cations in V - Al - O were seen even at low radiation doses. Absolute and relative shifts in binding energies along with changes of peak intensities and widths demonstrate that an appreciable amount of V5+ is reduced to lower oxidation states. X- ray induced chemical modi. cations extend at least to the depth sampled by the V3p electrons. It is suggested that the damage is caused by electron- hole pair generation and Auger decay. Al - O - H in V - Al - O is also affected by X- rays. This causes O-2 and water desorption as followed by mass spectrometry of the residual gas.