An additive free synthesis of nanocrystalline zinc oxide using microwave technique is reported. The current methodology is faster, cleaner and cost effective compared with conventional method for the synthesis of zinc oxide nanocrystalline materials. The structure and morphology of nanocrystalline zinc oxide was investigated by TEM, XRD, EDAX and UV-vis spectroscopy. The results demonstrate that microwave heating can produce polygonal zinc oxide within a short span of time. (C) 2010 Elsevier B.V. All rights reserved.