<p>Results are given for a study of the crystal structure and optical characteristics of disordered tin oxide films. The synthesis of these films was carried out by means of magnetron sputtering of a tin target on a glass substrate followed by two-stage annealing in the air. The microstructure of the tin oxide films was analyzed by x-ray diffraction and Raman spectroscopy. Transmission spectra of the samples were taken in the wavelength range λ = 200–3000 nm. The optical constants of the thin tin oxide films, namely, the refractive index n and absorption coefficient α, relative to wavelength were determined using the envelope method. Feasibility was shown for the preparation of tin oxide films with control of the optical parameters (absorption coefficient α up to 82% in the visible range of the electromagnetic spectrum, refractive index n in the range 2–2.6, and Tauc optical gap in the range 2.62–3.46 eV) by adjusting the temperature in the second stage of the oxidative annealing process in the range 325–475oC.</p>