Oriented SnO
2
nanowire (NW) arrays were grown on TiO
2
(001) substrates by molecule-based chemical vapor deposition of Sn(O
t
Bu)
4
. Preferred growth directions ([101], [-101], [011], and [0-11]) of SnO
2
NWs were correlated to surface energy consideration and crystallographic relationship between the substrate and NW material by comprehensive electron microscopy and bulk tomographic studies. The proposed growth incubation model (tilting of catalyst/NW interface due to driving force of surface energy) explains the formation mechanism of oriented SnO
2
NWs on TiO
2
substrates. These results allowed us to also study the I-V characteristics and gas-sensing properties of individual SnO
2
NWs grown with a perfectly defined crystal orientation ([101]).