Supported phospholipid bilayers have been often studied as mimics of biological cell membranes, in order to study lipid behaviour and lipid-protein interactions. These include investigations of lipid bilayers supported on Au electrodes, where the effect of an applied electric field (of comparable magnitude to that experienced in cell membranes) on bilayer structure has been determined. The natural compositional asymmetry across the two halves of a biological membrane is infrequently considered. Our electrochemical and IR measurements indicate that introducing asymmetry into bilayer structure has an influence on electrical properties and film response to the field. In this experiment, we propose to evaluate separately the solvent content and thickness of each half of an asymmetric bilayer, to enable us to understand the differences in behaviour between symmetric and asymmetric bilayers.