Poly(DNTD,N,N′-di[p-phenylamino(phenyl)]-1,4,5,8-naphthalenetetracarboxylic diimide) and its nanocomposite film incorporated withWO3 nanoparticles was prepared by a facile electropolymerizationmethod on an indium in oxide (ITO) coated glass slide from the DNTD monomer andWO3 nanoparticles suspended methylene chloride solution. Themorphology and microstructure of the nanocomposite film were characterized byscanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEMimage shows that the WO3 nanoparticles are uniformly embedded in thepolymeric matrix. The nanocomposite film also displays smooth topography withevenly sized and uniformly distributed nanoparticles under high resolution AFMobservations. An air-stable electrochromical window was assembled and obtainedby a homemade electrochemical cell to study the electrochromism and stability ofthe nanocomposite film. The composite film exhibits multiple colors at both thecathodic and anodic potentials, i.e., light blue at ?1.4 V, orange red at ?0.8V, colorless at 0 V, orange green at 0.8 V, light blue at 1.0 V, and deep blueat 1.2 or 1.4 V vs Ag/AgCl in propylene carbonate containing 1.0 MLiClO4 electrolyte. The UV–visible incorporated electrochemicalspectroscopy coupled with amperometry were also employed to study the compositefilm under different potentials in the range of ?1.4 to 1.4 V vs Ag/AgCl. Thecomposite film also shows stable electrochromism even after 100 scans. Thethermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) analysissuggest the hydrogen bonding formed between the monomers and WO3particles, resulting in an increased initial oxidation potential for the monomerduring the poly(DNTD)/WO3 nanocomposite film formation.