A new method for modeling electrode surfaces, applied to aluminum electrolysis, is presented. The method uses nonequilibrium thermodynamics for surfaces and describes the fluxes, the overpotential, and the dissipated energy at the surfaces in a new way. Examples are given for the interface anode- and cathode-bath to show how the model may be used to predict surface properties based on observed phenomena and the total energy dissipated in the cell. The method predicts apparent discontinuities at the surfaces in electrical propel-ties, as well as in temperature and in chemical potentials. The overpotential is viewed as a discontinuity in electrical potential. Local surface heating or cooling effects can be simulated, and the results can be used to estimate surface proper-ties. The calculations show that excess surface temperatures of magnitude 0.1 K can occur under certain surface conditions. If the excess surface temperature is of magnitude 1 to 10 K, unrealistically high dissipated energy at the surfaces results. At the anode surface, electrical conductivities as small as; 10(-7) times their respective bulk values lead to the measured value for anodic overpotential. Even smaller conductivities lead to larger overpotentials, and a typical anode effect value results if the electrical conductivities are smaller than 10(-8) times their respective bulk values.