SiO2 layers were deposited by reactive d.c ion sputtering (using 1 keV Ar+ ion gun) from a high purity silicon target in an oxygen ambient. The base pressure in the deposition chamber was 4.7-10(-9) mbar, and the substrate temperature was held at 550 degrees C. The argon partial pressure during ion gun operation was 1-10(-3) mbar. Structural characterization of the films was performed by Rutherford backscattering spectrometry (RBS analysis), electron microprobe analysis, X-ray diffraction (XRD analysis) and Raman spectroscopy. Reactive sputtering proved to be efficient for the deposition of silica at an oxygen partial pressure of 2-10(-4) mbar and an electrical current on the target of 5.5mA.