The electrochromic (EC) properties of inorganic-organic hybrids of tungsten oxide/reduced graphene oxide (WO3/rGO) thin films were examined. Using hydrothermal method WO3 nanorods were deposited on a conducting Indium-doped tin oxide (ITO) glass substrate. In succession, the reduced graphene oxide thin film was coated on WO3 thin film using improved Hummers method. The structural, morphological, optical, and electrochromic responses of WO3, rGO, and WO3/rGO films are illustrated. Compared with pure WO3 film, WO3/rGO composite film demonstrates improved EC performance because of enhanced double insertion/extraction of ions and electrons. It realizes a large optical modulation (58.8% at 633 nm) with a significant increase in Coloration Efficiency (CE) and EC stability. (C) 2020 Elsevier Inc. All rights reserved.