An aqueous solution method has been presented for synthesizing ZnO nanorod arrays with controllable diameter and lengths on different substrates. Thermal decomposition deposition was first used to grow a thin layer of ZnO nanocrystals on substrate serving as seeds for the subsequent growth of the nanorod arrays. X-ray diffraction analysis confirmed the high orientation of the ZnO nanorods. The effect of different substrates and the annealing temperature of the ZnO seeds on the morphology of the as-grown ZnO arrays were investigated. The diameter and the length of the nanorods can be controlled by the reaction times and reaction temperature. These highly oriented nanorod arrays are potential for the creation of functional materials, such as the electrode of the solar cells, photonic devices. etc. (c) 2006 Elsevier B.V. All rights reserved.