The behaviour of suphide species at a silver/electrolyte interface along with the electrodeposition of thin Ag2S films have been studied by a combination of electrochemical and in situ optical methods. The potential region between - 1.08 and - 0.470 V (nhe), pre-peak zone, is mainly characterized by a reversible process, at -0.870 V, overlapping and catalysing the her, ascribed to the formation of an Ag-(SH-)(ads) bond. Phase Ag2S deposits were found to fit a linear relationship between reflectance, in the blue region, and charge. The oxidation of surface Ag2S (postwave) is readily observed by differential reflectance at potentials positive of the onset of bulk Ag2S formation. The rough sliver surface brought about by the reduction of Ag2S allows a strong coupling between photons and surface plasmons.