An all solid-state electrochromic device (ECD) was formed by anodically colored polyaniline (PANI) and cathodically colored tungstic acid, WO3, 2H2O, separated by a protonic conductor solid electrolyte: poly 2-acrylamido 2-methylpropane sulfonic acid, (PAMPS). PANI as well as tungstic acid films were electrochemically deposited on SnO2. The transmission spectra of ECD were displayed using near IR/visible/near UV spectroscopy as well as optical multichannel analysis which allows, in addition, to obtain the kinetics of coloration/bleaching. They were checked after up to 2·104 electrochromic cycles extending from −1.2 to +1.2 V; the change of optical density, ΔOD, the coloration yield and the stability during the cycling were determined. The influence of the experimental parameters (electrolyte pH in the range 0.65–7.65, coloration potential) was studied; good coloration reversibility and memory effect can be obtained up to pH=7.65. A typical device presented a coloration time of ≈30 s and a shorter (<10 s) bleaching time, with ΔOD=0.4 at 2.23 eV (human eye maximum sensitivity), falling to 0.25 after 2·104 cycles. The choice of PAMPS as a solid electrolyte has many advantages: its pH can be set to the best value, rather high, and the structure of the PANI/PAMPS interface allows to explain the presence of conductivity even at high pH. The excellent reversibility of ECD is associated to the presence of an optical free-carriers tail.