A new nanocomposite WO3 (NWO) film-based electrochromic layer was fabricated by a spray and electroplating technique in sequence. An indium-tin oxide (ITO) nanoparticle layer was employed as a permanent template to generate the particular nanostructure. The structure and morphology of the NWO film were characterized. The optical and electrochromic properties of the NWO films under lithium intercalation are described and compared to the regular WO3 film. The NWO films showed an improved cycling life and an improved contrast with compatible bleach-coloration transition time, owing to the larger reactive surface area. The nanocomposite WO3 film-based electrochromic, device (NWO-ECD) was also successfully fabricated. Most importantly, the NWO, film can be prepared on a large scale directly onto a transparent conductive substrate, which demonstrates its potential for many electrochromic applications, especially, smart windows, sunroof and displays. (c) 2007 Elsevier B.V. All rights reserved.