In this study, different organic additives such as beta-cyclodextrin (beta-CD), amylose, and poly(ethylene oxide) polymer (PEO) are selected, respectively, to coat zinc acetate in order to investigate their roles on the thermal decomposition process of the precursor. Accordingly, the morphology and size of the produced ZnO nanoparticles are strongly affected by the existence of organic additives through XRD analyses and TEM observations. Among the selected additives, beta-CD is proved to be the most favorable for the preparation of uniform ZnO nanoparticles. Besides, the size of ZnO can be controlled by changing the beta-CD/zinc acetate concentration ratio. The possible formation mechanism of ZnO nanoparticles by the coating of the above organic additives on zinc acetate in thermolysis is also discussed. (C) 2003 Elsevier B.V. All rights reserved.