Controlled growth of oxide nanowires is an emerging research field with many applications in, for example, electronics, energy production and storage, security, and life science. A great number of theoretical and experimental studies have been carried out on the model of growth of semiconducting nanowires, while the systematic analysis of oxide nanowires is still missing. We have examined the morphological and structural features Of In2O 3nanowires grown on single crystal substrate, catalyzed by gold clusters, to investigate the basic growth mechanisms of oxide nanowires. These nanowires exhibit a bodycentered cubic structure and grow along the [100] vector of the cubic crystalline cell, thus being an ideal system for modeling nanowire nucleation and growth, without any preferential direction due to cell anisotropy. Bare vapor-solid (VS) or vapor-liquid-solid (VLS), which are the commonly accepted growth mechanisms, cannot account for the complete description of oxide nanowire growth. The experimental findings can be satisfactorily explained under the hypothesis of concurrent direct VS and catalyst-mediated VLS mechanisms during nanowire growth, with the formation of high-index lateral faces which regulates longitudinal elongation at high temperature, according to the periodic bond chain (PBC) theory. 2009 American Chemical Socieiy.