Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO nanostructures. ZnO nanostructures have been synthesized using sol–gel immerse technique on oxidized silicon substrates. Different precursor's concentrations ranging from 0.0001 to 0.01 M using zinc nitrate hexahydrate [Zn(NO3)2.6H2O] and hexamethylenetetramine [C6H12N4] has been employed in the synthesis of ZnO nanostructures. The surface morphologies were examined using scanning electron microscope (SEM) and atomic force microscopy (AFM). In order to investigate the structural properties, the ZnO nanostructures were measured using X-ray diffractometer (XRD). The optical properties of the ZnO nanostructures were measured using photoluminescence (PL) spectrometer.