TiO2 nanocrystals embedded amorphous WO3 electrochromic films have been successfully fabricated with a facile one-step solution process. The structure and electrochromic properties of composite films were studied by transmission electron microscope, scanning electron microscope, X-ray diffraction, Raman spectroscopy, and electrochemical methods. The results show that anatase TiO2 nanocrystals with a size of about 5-10 nm were homogeneously embedded in the amorphous WO3 matrix (TiO2@WO3). Compared with pure WO3 film, the electrochromic performances of TiO2@WO3 are evidently enhanced. The further electrochemical analysis indicates that the enhancement may be mainly ascribed to the reconstruction of amorphous WO3 matrix with the emerging interfaces between nanocrystals and amorphous matrix. And the extremely high value of the coloration/bleaching reversibility is associated with the suppressing effect of TiO2 nanocrystals upon the Li+ trapping in WO3 matrix. (C) 2019 Elsevier Ltd. All rights reserved.