Amorphous dielectric gallium phosphate thin solid films of various compositions were deposited on silicon substrates by the 'pyrosol' process. This paper reports on the results of a structural investigation of these deposits, before and after annealing, by infrared spectroscopy. Moreover, the AWAXS technique was used to probe the medium range order around Ga atoms in an as-grown deposit. For P-rich thin films, both the Ga and the P atoms exhibit tetrahedral surroundings. The phosphorus excess is present in form of [P-O-P](n) chains. In Ga-enriched deposits, GaO6 sites are predominant, and the PO4 tetrahedra do not any longer form P-O-P bridges. Only GaO4 tetrahedra are present in the annealed P-rich compositions, and the [P-O-P](n) chains have disappeared. For Ga/P > 1 deposits, the annealing leads to an important reduction of the GaO6 site proportion.