A polymerizable sol-gel approach has been employed to synthesize bulk and nano-crystalline WO3. A W-containing sol-gel resin is formed and subjected to thermally induced free radical polymerization followed by calcination at 450, 650 and 850 degrees C. TGA analysis was performed to reveal the calcination temperature required for WO3 formation. The synthesized oxides have been characterized with XRD, SEM, XPS, TEM and diffuse reflectance spectroscopy to probe the crystallinity, surface morphology and electronic structures. BET surface area measurements were carried out for the synthesized materials to follow the effect of calcination temperature on surface area. The calcination temperature was found to be crucial in tuning the crystallinity and non-stoichiometry of the materials. The synthesized catalysts were explored for the efficiency of Cr(VI) photoreduction in aqueous medium under visible light and the results are correlated with the structural and electronic properties of the materials. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.