Actinomorphic GaN nanowires clusters have been achieved by ammoniating Ga2O3 thin films deposited on the Mg layer on the Si (111) substrate. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). SEM images show that the resulting materials are actinomorphic nanowires clusters with the glazed surface. XRD, HRTEM and SAED indicate that the nanowires are single-crystal hexagonal GaN with a wurtzite structure. (c) 2006 Elsevier B.V. All rights reserved.