The stability of a number of transparent conducting oxide (TCO) films prepared by magnetron sputtering has been tested in various atmospheres at high temperatures up to 1000 degrees C: binary compounds such as ZnO, In2O3, and SnO2; ternary compounds such as Zn2In2O5, In4Sn3O12, GaInO3, ZnSnO3, and MgIn2O4; and multicomponent oxides composed of combinations of binary compounds or ternary compounds. With regard to the stability of the electrical properties, In2O3, SnO2, and SnO2:Sb films were stable in an Ar gas atmosphere at temperatures up to 900 degrees C. SnO2 and SnO2:Sb films were stable in air at temperatures Up to 900 degrees C, and In2O3 and ITO were stable in air at temperatures: up to 800 OC. Although the ZnO:Al film was stable in an Ar gas atmosphere at temperatures up to 600 degrees C, it was unstable in air at temperatures above 400 degrees C. The stability improved as the Sn content in Sn containing TCO films was increased, but it lessened as the Zn, Mg, and/or Ga contents were increased. In addition, the chemical stability at high temperatures was mainly determined by the metal elements contained in the TCO film; TCO film rich in Sn were very stable.