The effect of solvent composition on the growth of ZnO crystals has been investigated in water-ethanol solution system. Ethanol is found to effectively inhibit the crystal growth along the < 0001 > direction, leading to the formation of thin disks. Hexagonal nanodisks and near-rounded microdisks have been grown in 1:1 (volume ratio) and 1:9 water-ethanol solutions, respectively. Transmission electron microscopy and selected area electron diffraction results show that the prepared hexagonal nanodisks have a single-crystal structure. In contrast, the near-rounded microdisks have a layer-by-layer structure, suggesting that crystals are grown by outward attachment. A strong sharp UV luminescence and a weak broad green-yellow emission in photoluminescence spectra indicate a high crystal quality of the prepared ZnO nano(micro)disks. (c) 2008 Elsevier B.V. All rights reserved.