Electrical, optical properties, and microstructures of ZnNb2O6 thin films prepared using the sol-gel method on ITO/glass substrates at different annealing temperatures have been investigated. The surface structural and morphological characteristics analyzed by X-ray diffraction, scanning electron microscopy, and atomic force microscope were found to be sensitive to the deposition conditions, such as annealing temperature (500 degrees-700 degrees C). Optical properties of the ZnNb2O6 thin films were obtained using UV-visible recording spectrophotometer. The selected-area diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. All films exhibited ZnNb2O6 (031), (131), (060), and (162) orientation perpendicular to the substrate surface and the grain size with the increase in the annealing temperature. At an annealing temperature of 700 degrees C, the ZnNb2O6 films with 55 nm thickness possess a dielectric constant of 24 at 1 kHz, a dissipation factor of 0.16 at 1 kHz, a leakage current density of 7.04 x 10-6 A/cm2 at an electrical field of 30 kV/cm, and an optical bandgap of 3.9 eV.