The electrical and optical properties of rf‐sputtered Sn‐doped In2O3(ITO) films have been found to depend strongly on the O2partial pressure during deposition. For the sputtering conditions used, films with both low electrical resistivity (&rgr; ∼ 3 × 10−4&OHgr; cm) and high visible transmission (∼ 90%) were obtained only over a narrow range of O2pressures, from 3 × 10−5to 4 × 10−5Torr. Our results appear to explain the difficulties that have previously been encountered in obtaining high‐quality ITO films, and indicate that control of the O2pressure during deposition is essential for reproducible preparation of such films.