Well-defined flower-like ZnO microstructures with different sizes and shapes have been successfully synthesized via a simple aqueous solution route, using zinc chloride and sodium hydroxide as the reactants, triethanolamine (TEA) as the modifying agent. The XRD pattern indicated that the obtained ZnO microcrysials were of wurtzite structure. SEM and TEM images illustrated that the flower-like ZnO bundles consisted of some prism-like or petal-like branches, which can be further characterized as single crystals in nature and preferentially growing up along [000 1] by SAED and HRTEM studies. The solution basicity has determinative effects on the morphology, size, as well as dimensionality of the obtained Zn0 microcrystals by mediating the nucleation and crystal growth rate. Furthermore, the uneven adsorption of TEA on (0 0 01) plane of the growing ZnO crystal leads to the tapering feature of the branches, which resemble vividly the flower petals in appearance. (C) 2007 Elsevier B.V. All rights reserved.