An examination of structural modifications, induced by mixing vanadium and cerium oxides and by the introduction of lithium in vanadium and mixed vanadium/cerium oxide films, was performed using synchrotron sourced grazing incidence small-angle X-ray scattering. Samples were sol-gel-derived films, deposited by a dip-coating technique. An analysis of the scattering data, acquired by a two-dimensional detection system, is based on the comparison of the surface and bulk characteristics of the film. The trend of estimated structural modifications is supported by the results of previous investigations on a different length scale, performed by atomic force microscopy.