High-density and uniformly aligned tungsten oxide nanotip arrays have been deposited by a conventional thermal evaporation on ITO glass substrates without any catalysts or additives. The temperature of substrate was 450-500 degrees C. It was shown that the tungsten oxide nanotips are single-crystal grown along [0 1 0] direction. For commercial applications, field emission of the tungsten oxide nanotip arrays was characterized in a poor vacuum at room temperature. The field emission behaviors are in agreement with Fowler-Nordheim theory. The turn-on field is 2.8 V mu m(-1) as d is 0.3 mm. The excellent field emission performances indicated that the tungsten oxide nanotip arrays grown by the present approach are a good candidate for application in vacuum microelectronic devices. (c) 2007 Elsevier B.V. All rights reserved.