ITO films deposited on ZrO2 undercoats by sputtering were investigated. The ITO films have a fine grain structure, compared to a grain-subgrain structure of conventional ITO films grown on a glass substrate. The grain structure of the ITO films grown on ZrO2 consists of 30-50 nm wide almost parallel-sided columns. The surface grains have a good uniformity in shape and size. The microstructure and electrical properties of the ITO films changed with increasing ZrO2 thickness. This indicates that the microstructure and properties of ITO films can be controlled by the ZrO2 film thickness. The OLED fabricated on the ITO films on ZrO2 worked with lower driving voltage than the one fabricated on conventional ITO films at the same luminance. (C) 2003 Elsevier B.V. All rights reserved.