In this work, relationships between chemical and physical properties of fluorine doped tin oxide films prepared by the chemical spray pyrolysis technique have been studied. Changes in the structural, optical and electrical properties of these films in relation to their doping concentrations determined by the resonant nuclear reaction analysis and x-ray photoelectron spectroscopy (XPS) techniques have been correlated. By XPS measurements, it was found that the fluorine content in the tin oxide films does not induce any chemical shift of the Sn and O core levels. At the same time, XPS measurements are carried out at low binding energy, shown that the valence band of heavy doped tin oxide changes with respect to that determined in SnO2 powder, due to the influence of the fluorine doping. In addition, it was shown that the formation of F–Sn complexes provides a decrease in both the concentration and mobility of the carriers.