Alumina oxide nanowires were grown via a two-step anodization of aluminum foil. A growth mechanism is proposed for these nanowires which is different from that of those formed using chemical etching methods. An electric field and stress are necessary to grow these nanowires, and the nano-imprinted metal surface of the aluminum foil has an important role. PAAO, porous alumina oxide, aluminum anodization, nanowiresCitation: Zhu K G, Cheng J R, Chang M C, et al. Growth of alumina oxide nanowires in an aluminum anodization process. Chinese Sci Bull, 2011Bull, , 56: 1947Bull, -1950 Nanoscale alumina oxide structures have been obtained using electrochemical methods. Alumina oxide nanotubes with many branches were fabricated via the anodization of aluminum on a silicon substrate in dilute sulfuric acid [13]. Alumina oxide nanotubes and nanowires were produced by chemically etching PAAO membranes either in sodium hydroxide solution [14,15] or in phosphoric acid solution [15][16][17][18][19][20]. However, to the best of our knowledge, there are few reports of the formation of alumina oxide nanowires in organic acid solution. Moreover, there have been no comparisons between the growth of nanowires in an etching process and that in anodization. In this work, alumina oxide nanowires are obtained after a two-step anodization of an aluminum foil. A growth mechanism is proposed for these nanowires. This proposal should be conducive to studies on the self-ordering mechanism of cells during the anodization of porous aluminum.