The ion-beam-induced chemical vapor deposition (IBICVD) method has been used for the preparation of TiO2, Al2O3 and mixed oxide AlnTimOx amorphous films on silica substrates. Also, a double-layer Al2O3/TiO2 film has been prepared. The reflectivity (low angle X-ray diffraction) technique, together with transmission electron microscopy (TEM) and UV–Vis absorption spectroscopy, have been used to get information about thickness, roughness and electronic density of the films. It has been found that the films are homogeneous and flat being the Al2O3 layers less dense than the TiO2 layers. In particular, AlnTimOx films can be prepared with variable composition and refraction index. The values obtained for electronic density by X-ray reflectivity have been correlated with the compaction degree of the films as stated from TEM and UV–Vis absorption spectroscopy studies.