Thin (SnO2)х(In2O3)1 –х (x = 0–1) films on the order of 500 nm in thickness have been produced on hot (400°C) substrates by RF magnetron sputtering of ceramic targets with various compositions. The phase composition of the films has been determined by X-ray diffraction, and the formation of the In4Sn3O12 phase has been demonstrated at x = 0.3. The solubility limit of In in SnO2 and Sn in In2O3 has been estimated at about 10 wt %. All of the grown films have been shown to be transparent in the visible spectral region. We have determined the transmittance, absorption coefficient, and band gap of the films. The results demonstrate that the formation of the In4Sn3O12 phase is accompanied by a decrease in band gap to 3.3 eV. Infrared transmission measurements have shown that the (SnO2)х(In2O3)1 –х films with x = 0.1 do not transmit infrared radiation and can be used as thermal mirrors. Carrier concentration and mobility in the (SnO2)х(In2O3)1 –х films have been determined over the entire range of x values using Hall effect measurements. These parameters are largest in the x = 0.1 (ITO) films: n = 9.1 × 1021 cm–3 and μ = 81.3 cm2/(V s). The x = 0.9 films have the highest sheet resistance and can be effectively used as gas sensors. The sensitivity of the films to ethanol vapor in air has been assessed.