Four reverse opal structured PEDOT (R-PEDOT) films with different pore size are obtained via electrochemical deposition of PEDOT on PS opal templates and then removal of the PS microspheres. The surface morphology, reflection spectra and electrochromic properties of the R-PEDOT films are measured. SEM images clearly show the R-PEDOT films have ordered 3D nano-sized hemispherical pore as face-centered cubic structure, which are typical reverse opal structures. When being observed from different angles, all the R-PEDOT films present rainbow effect. Besides, the four R-PEDOT films have similar electrochemical performance, higher current values and larger rectangular areas in an order of R-PEDOT 242 > R-PEDOT 173 > R-PEDOT 318 > R-PEDOT 290 > PEDOT. Compared with the pure PEDOT film, the R-PEDOT films have increased contrasts, higher chromatism values and richer color information. Unexpectedly, their response times have decreased a little, which may result from the poor adhesion between R-PEDOT films and the ITO glass surface. To sum up, the R-PEDOT films have better electrochromic properties than the pure PEDOT film, and no linear relationship exists between electrochromic properties and their pore size. [ABSTRACT FROM AUTHOR]