The growth of polypyrrole (Ppy) layers on gold electrodes in nearly neutral pH solutions is analysed using "in situ" voltametric and ellipsometric techniques. Different film structures are obtained depending on the potentiodynamic programme and the composition of the electrolyte. More compact dodecylsulphate-(DS) doped Ppy layers were grown at 1.2 V versus RHE than those obtained by applying a higher potential. The more compact layers correspond to the growth of an oxidised Ppy/DS layer that shows low pseudo capacity behaviour. After dipping, the doped Ppy/DS film in KCl solution-significant variations in optical indices and thickness are detected as a function of the applied potential. Higher electrochromism as well as decrease in film thickness after cathodisation is achieved. The optical indices and the thickness of the Ppy layer formed under different applied potential/time programmes are estimated.

The properties of the confined aqueous layer potentiodynamically formed on polycrystalline gold in aqueous phosphate and sodium dodecylsulphate solutions were studied using voltammetry, ellipsometry, and contact angle measurements. The nature of the incipient oxide layer was analyzed as a function of the cycling time in the double layer-oxide monolayer potential region. The replacement of the electrolyte by hexane allows the increase of the optical signal. Different potential cycling conditions change the homogeneity of the confined aqueous incipient oxide layer leading to different structural characteristics.