Single-crystalline Se nanowire arrays have been fabricated by electrodeposition using anodic porous alumina templates. The microstructures of Se nanowires were sensitive to the deposition condition. The nanochannels in the template not only determined the morphology of Se nanowires but also influenced their microstructures. We found Se nanowires deposited at 40 degrees C were an uncommon Se face-centered cubic structure, which was determined to be CaF2 type. The phase transformation in Se nanowires has been studied by Raman spectroscopy and transmission electron microscopy. (c) 2004 Elsevier B.V. All rights reserved.