This paper will address how core level and valence band X-ray photoelectron spectroscopy can be used to study the chemical composition of the surface films on aluminum alloys. Certain alloying elements may preferentially migrate to the surface, thereby altering the composition and consequently the chemistry of the surface. Magnesium and silicon are known to preferentially migrate to the surface of the 6061 aluminum alloy but the chemical nature of the films formed on the surface is not well understood. The surface films can be identified by core level and valence band X-ray photoelectron spectroscopy. It will be shown that the type of magnesium film formed at the surface can be determined by comparing the valence band spectra of the aluminum alloy surface with that of the model compounds, magnesium oxide, magnesium hydroxide and the magnesium aluminum oxide. The effect of boiling water on the surface film will be discussed. It will also be seen that valence band photoemisson spectra, interpreted by band structure calculations, is a very effective tool for the conclusive identification of the surface species present. This material is based upon work supported by Luxfer Gas Cylinder.