A series of electrochromic hybrid materials were synthesized with in-situ polymerization of aniline, 2-fluoroaniline and N-methylaniline onto tungsten trioxide (WO3) powders using a rotating capacitively coupled radio frequency (rf) plasma process. The materials were characterized by means of scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction analysis (XRD). Thin films of tungsten trioxide/polyaniline (WO3/PANI), tungsten trioxide/poly(2-fluoroaniline) (WO3/PFANI) and tungsten trioxide/poly(n-methylaniline) (WO3/PMANI) hybrid powders were obtained by e-beam technique onto flexible conducting polyethylene terephthalate electrodes for electrochromic works. The optical and electrochromic properties of WO3 hybrids-based ECDs were investigated by optical and electrochemical measurements. It is observed that electrochromic performance of hybrid films has changed as depending on electron acceptor or donor properties of substituent group onto PANI chain. The results of flexible electrochromic devices (ECDs) indicated that WO3/PMANI hybrid-based ECD has a high optical contrast of 49% at 750 nm, reversible coloration with efficiency of 361 cm(2)/C and fast switching times (bleaching time: 1.41 s, coloration time: 0.67 s).