Planar positively-charged gold electrode surfaces were modified by consecutive adsorption of poly(styrene sulfonate), PSS, and protonated poly(allyl amine), PAH. By varying the sulphuric acid concentration in the PAH adsorption solution it was possible to obtain films with two different thicknesses. The permeability of the two types of self-assembled films was probed by studying the cyclic voltammetric response with two electroactive species in the supporting electrolyte; i.e. an anion, Fe(CN)(6)(4-) and a cation, Os(bipy)(3)(3+). Electrochemical impedance spectroscopy was also employed in the characterisation of the films.