We report the formation of beta-FeSi2 nanowires (NWs) on Si(110), produced by annealing s-FeSi2 NWs at 800 degrees C. These two phases of iron silicide are semiconducting and metallic, respectively, in thin film form. The s-phase NWs are formed by reactive deposition at 700 degrees C and have average dimensions of 5 nm thick x 8 nm wide x 3 pin long. Both are endotaxial, meaning they grow into the substrate along inclined Si{111} planes. The transformation temperature is higher than observed in thin films, due to the small thickness and large interface area of the NWs, which stabilize the s-phase. (c) 2006 Elsevier B.V. All rights reserved.