The current research activities focus on the Zinc Oxide (ZnO) nano structured materials and their physical characterization due to their widespread applications in optoelectronic as blue colour light emitting phosphors,as nanorod UV light emitters, as fluorescence labels in medicine and biology but also in cosmetic industry as ingredient in sunscreens. Zinc Oxide nano powders are also well suited to electronic applications such as capacitors varistors, photo printing and electro photography due to extremely low levels of heavy metal impurities. These recent findings are now proven that ZnO nanopowders are bio- safe and bio-compatible. This book provides a low cost, easy and simple method of synthesis of ZnO nanopowder using Domestic Microwave Oven.Zinc Acetate and Sodium Hydroxide are used as starting materials. The prepared ZnO nanopowder has been subjected to various analyses. The average particle sizes have been found to be in the nanometer range.