ZnGa2O4:Cr3+ thin films with bright red emission were synthesized using a sol-gel process, characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Auger electron spectroscopy (AES) and UV-vis and fluorescence spectrophotometry measurements. Effects of calcining temperature, film thickness, calcining duration and substrates on the crystal structure and photoluminescent property have been investigated. It is found that the crystallinity, Ga/Zn ratio and band gap energy (E-g) are significant factors influencing optical characteristics, while the nature of substrates affect the surface morphologies of ZnGa2O4:Cr3+ thin films. (C) 2010 Elsevier B. V. All rights reserved.