Zinc oxide (ZnO) nanopowders were synthesized by the sol–gel method from an ethanol solution of zinc sulfate heptahydrate in the presence of diethylene glycol surfactant. Detailed structural and microstructural investigations were carried out using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer. XRD pattern showed that the zinc oxide nanoparticles exhibited hexagonal wurtzite structure. The average particle size of ZnO was achieved around 28 nm as estimated by XRD technique and direct HRTEM observation. The surface morphological studies from SEM and TEM depicted spherical particles with formation of clusters. The sharp peaks in FTIR spectrum determined the purity of ZnO nanoparticles and absorbance peak of UV-Vis spectrum showed the wide bandgap energy of 3.49 ev.