Electrical and optical properties of SnO2, which is a photovoltaic material for solar energy conversion to electricity, have been investigated. Semi-conducting SnO2 has been grown by r.f. sputtering. We report the influence of process variables, such as substrate temperature and r.f. power. The film resistivity decreases with increasing temperature, but rises with increasing r.f. power: these can be related to crystallite size and the film orientation respectively. From the optical measurements, we deduce a variation of band-gap energy with substrate temperature. We show that the substrate temperature has a subsequent influence on the electrical and optical properties of this material.