AlxTiyOz thin films (i.e., mixture of Al2O3 and TiO2) with different Al/Ti ratios have been characterized by several electron spectroscopies. The Auger parameter of Ti, determined by x-ray photoelectron spectroscopy, increases with the percentage of Ti in the films. The same trend is found for the evolution of the refractive index in the visible region no, that, as measured by UV-Vis absorption spectroscopy, varies from 1.5 to 2.5 as a function of the percentage of Ti. Within the same range of compositions, the Auger parameter of Ti changes by 1.2 eV. Such behavior permits an empirical use of the Auger parameter to assess optical parameters of this type of films. On the other hand, reflection electron energy loss spectroscopy has provided information on the optical properties of the films in the far-ultraviolet region (55 eV, which produces a modulation in n(nw), that depends ori the film composition. As a consequence, it is concluded that the correlation between the Auger parameter and the refractive index in the visible region does not hold when other energies are considered.