Morphology-tuned ZnO microcrystals can be prepared by oxidizing zinc metal substrates in aqueous solution using hydrothermal technique. Some typical ZnO growth morphologies such as nanorod superstructures, nanorod arrays, microspheres, hierarchical nanostructures, and split crystals have been chemically fabricated. These microscopic shapes can be finely controlled by selecting Zn(NO(3))(2) concentration and solvent. A conceptual model was proposed to explain the formation of the as-prepared ZnO structures by selecting proper kinetic environments. This one-step, wet-chemical approach is controllable and reproducible, which can be conveniently transferred to industrial applications. (C) 2009 Elsevier Ltd. All rights reserved.