Zinc niobium oxide (ZnNb2O6) thin films were grown on ITO/glass substrate by sol-gel process. Microstructure and surface morphology of the ZnNb2O6 thin films have been studied by X-ray diffraction and scanning electron microscopy. Optical properties of the ZnNb2O6 thin films were obtained by UV-visible recording spectrophotometer. The dependence of the microstructure, optical transmittance spectra, optical band gap on annealing temperature was also investigated. (C) 2011 Elsevier B.V. All rights reserved.