This paper describes a new type of resistive TiO 2 oxygen sensor that can be used for monitoring and control of combustion processes such as the combustion in an engine. In contrast to the existing ceramic TiO 2 sensors, the new sensor is based on TiO 2 films grown by chemical vapour deposition from organometallics such as tetraisopropyl titanate. The condition for obtaining films with the stable rutile phase and the required properties are discussed. The electrical properties of these films were studied in the range 300 – 900 °C for oxygen pressures between 1 and 10 −35 atm and were generally found to be similar to those of TiO 2 ceramics. With the addition of noble metal catalysts, these films are capable of measuring the thermo-dynamic equilibrium oxygen pressure and can thus be used as stoichiometric air-to-fuel sensors. The properties of experimental TiO 2 film devices were studied in the laboratory and on engines. The main result is that these film sensors possess a faster transient response than available ceramic TiO 2 and electrochemical ZrO 2 oxygen sensors. In addition to having improved performance, film-type TiO 2 sensors can be inexpensively fabricated with multi-component structures for heating or temperature compensation.