Nanostructured Ge granular thin films were prepared by magnetron sputtering of composite targets pressed from mixtures of Ge and ceramic powders. The ceramics used were Al2O3, MgO and SiO2. Films in the Gex(Al2O3)l-x system were composed of Ge particles 10-60 nm in size uniformly embedded in the ceramic matrix, particularly for low Ge concentration films. X-ray photoelectron spectroscopy (XPS) was used to characterize these films. Samples were identified according to the coordination of Ge with the oxygen as (i) Ge-Ge4, (ii) Ge-Ge3O, (iii)Ge-Ge2O2, (iv) Ge-GeO3 and (v) Ge-O4. Using the modified Sanderson model1 and its modifications2, we found Ge oxidation to be largely composition dependent. Similar results were obtained for Ge granular films in MgO and SiO2 matrices.