Thin films of undoped and fluorine-doped tin oxide have been prepared on fused silica substrates by a spray pyrolysis technique. Structural, optical and electrical properties were studied. Fluorine doping increased the degree of crystallinity and preferred orientation as well as the figure of merit (23.9×10⁻³ at 0.5 µm). The refractive index,n, showed a considerable decrease (2.2−1.85) on fluorine doping. The direct allowed transition for fluorine-doped tin oxide was 0.1 eV higher than that of undoped material.