The optical characterization in the visible wavelength range was obtained for an electrochromic material, poly-3, 4-ethylenedioxy-thiophene (PEDOT), as a function of its redox charge density (charge consumed for the color change between its maximum and minimum absorbance states). The experimental procedure was kept very simple and all the information can be obtained from only one film, including the identification of the maximum achievable contrast for the material. Different films of the electrochromic material were tested in order to check the validity of the predicted values, showing excellent agreement.