A simple method was used to prepare monodispersed ZnO nanoparticles, which can be used as seeds for the synthesis of [0 0 0 1]oriented ZnO nanorods by refluxing. Based on the observation of shape and size of ZnO nanocrystals at different refluxing times and surface and attachment energies for various crystallographic planes calculated from the BFDH and HP models, a possible growth mechanism for ZnO nanorods was put forward to explain the experimental observations. The synthesized ZnO nanocrystals show green emission, which are correlated with the degree of oxygen vacancies in the samples. (C) 2007 Elsevier B.V. All rights reserved.