This investigation reports on the growth of ZnO nanotubes on patterned Au/Al2O3/Au/RuO2 templates by reactive evaporation and the fabrication of a ZnO nanotube ethanol gas sensor. The as-grown ZnO nanotubes were polycrystalline and had holes at their terminals and sidewalls. Injection of ethanol gas reduced the resistivity of the fabricated sensor. Introducing 100 ppm ethanol gas increased the measured sensitivities of the ethanol gas sensors from 34 to 87% as the temperature increased from 90 to 230 degrees C. Additionally, the sensitivity of the sensor increased with the concentration of injected ethanol gas. (C) 2008 The Electrochemical Society.