Polyaniline (PAni), polypyrrole (PPy) and their bilayer coatings on ITO coated glass were prepared by electropolymerization method. Morphological and spectroelectrochemical properties of these films depending on the thickness and the sequence of the coated polymers (PAni/PPy or PPy/PAni) were analyzed. Cyclic voltammetry, UV vis spectroscopy and scanning electron microscopy techniques were conducted to investigate the properties of bilayer coatings. Thickness of the second layer varies, depending on the thickness and type of the first layer. Furthermore, the optical transmittance varies with the sequence of the polymers. Delta T% values obtained from thin coatings of PAni/PPy bilayers are higher than the values obtained from the single layer films of each polymer. These differences have been attributed to morphological differences of bilayer films. Mono and bilayer ECDs have been constructed and investigated comparatively. As a result of the study, we have seen that bilayer films of PPy and PAni have better electrochemical stability than monolayer ECDs of each polymer. (C) 2013 Elsevier Ltd. All rights reserved.