A model for the diffusive and convective transport of rigid, spherical solutes through slit-shaped pores is used to examine electrostatic effects on solute exclusion by charged pores. This model includes steric and hydrodynamic drag, repulsive electrostatic interactions and pore size distribution represented as a log-normal probability density function. Analytical expressions for the effective diffusion coefficient and for the asymptotic sieving coefficient are obtained. To test theoretical predictions, experimental values of these coefficients are determined from diffusion and convection experiments conducted with globular proteins at various ionic strengths. Ultrafiltration and microfiltration membranes pore sizes are characterized after sieving measurements of neutral dextrans. Experimental and theoretical results are in fairly good agreement except for the microfiltration membrane.