The frequency and thickness dependence of the impedance have been studied both for the system Bi/Bi2O3/electrolyte and for the anodic Bi2O3 film itself and they appear to be influenced by the kind of contact electrolyte used. The dielectric permittivity of anodic Bi2O3 films is also different when aqueous (ϵ(1 kHz) = 48.5) and glycol borate (ϵ(1 kHz) = 45) electrolytes are used for contact. The values of ϵ differ considerably from the literature data available, the latter being affected by an incorrect refractive index used for obtaining the film thickness. The frequency dependences of the film capacitance and resistance are found to obey some general relations valid for the anodic oxides of a range of metals.