Mixed morphology of SnO2 nanowires and nanodendrites was synthesized on the gold-coated alumina substrates by carbothermal reduction of SnO2 in closed crucible. The products were characterized by scanning electron microscopy, x-ray diffractometer, and transmission electron microscopy. Results showed the SnO2 nanowires and the SnO2 nanodendrites branched out from the main nanowires. Both SnO2 nanostructures were pure tetragonal rutile structure. The nanowires were grown in [101] and [121] directions with the diameter of 50-150 nm and the length of a few 10 μm. The nanodendrites were about 100-300 nm in diameter. The growth mechanism of the SnO2 nanostructures was also discussed. Characterization of ethanol gas sensor, based on the mixed morphology of the SnO2 nanostructures, was carried out. The optimal temperature was about 360 °C and the sensor response was 120 for 1000 ppm of ethanol concentration. © 2011 Elsevier B.V. All rights reserved.