This investigation reports the synthesis of high-density, single-crystal Al-doped SnO2 nanowires on sapphire substrate by vapor-liquid-solid method. The length of and diameter of the SnO2:Al NWs is 7 similar to 8 mu m and 50-300 nm, respectively. The Al is protected by the Au/Pd in the drop of catalyst, it avoids oxidation and continuously provide Al to the SnO nanowires. The Al-doped concentrations were approximately 2.62 atomic%. Al induces a change in SnO2 crystals from a tetragonal rutile to cubic structure. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.068205jes]