Tuning the colour of electrochromic conducting polymers can be achieved by layer upon layer deposition of multiphase components. This approach can offer advantages over other approaches but requires detailed knowledge of the polymer interfaces. We propose NR measurements on bi-layer electroactive polymer films. The films will be electrochemically fabricated from the 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) and will be subject to electrochemical potential control to define charge state (¿doping level¿). The two central issues are the degree of inter-penetration of the two polymer components and the solvent distribution within each of thee layers and in the film as a whole. The specific objectives are determination of: i) individual polymer component spatial profiles, (ii) equal vs differentiated solvation of polymer components, iii) absolute solvation levels.