Streaming potential, electroviscous effect, pore conductivity and membrane potential were measured for a ceramic ultrafiltration membrane at various KCl concentrations. A space charge model was used to calculate the surface potentials from the experimental data. Surface potentials determined from the four experimental methods are in relatively good agreement although some discrepancies occur at low ionic concentrations. Pore conductivity and membrane potential methods lead to similar surface potentials on the whole range of concentrations studied but these latter are smaller than those obtained for both streaming potential and electroviscous effect measurements.