Ionic transport coefficients are numerically calculated in various porous media for high zeta potentials zeta by solving the Poisson-Boltzinann, the Stokes, and the convection-diffusion equations on the pore scale. Theoretical formulae for the simple case of a plane Poiseuille flow are derived in this limit. These formulae, when expressed in terms of the characteristic length Lambda, provide an excellent estimate of the ionic transport coefficients whatever the porous medium and whatever the value of zeta. (c) 2007 Elsevier Inc. All rights reserved.