The Stern layer has been included in the description of electrolytes in a charged porous medium, with possibly large zeta potentials. The surface charge density, the conductivity, and the electroosmotic coupling coefficient are calculated for various porous structures and various physicochemical conditions. The saturation of the Stem layer is analyzed, as well as its consequences for the macroscopic properties of the medium. The discontinuous character of the solid interface has an important influence on the macroscopic conductivity and the electroosmotic coefficient. (C) 2007 Elsevier Inc. All rights reserved.