Wicke-Kallenbach (WK) cells are often used for studying separation and component transport in porous material. In order to obtain important transport parameters, mathematical models are frequently developed but they generally consider the fluid phase in the WK compartments to be free of concentration gradients and thus external mass transport resistance is neglected. The present work is a detailed study of how the external transport influences permeation through porous material in a WK cell. External mass transfer effects were demonstrated experimentally and they were further studied from three-dimensional (3-D) model simulations. Film theory was applied to develop an appropriate Sherwood number correlation for the external mass transport coefficient. it was shown that the flow in the compartment and geometrical factors of the WK cell had significant influences on the permeation. It was found that introducing the proposed external mass transport correlation into a simplified one-dimensional (1-D) model was adequate to reproduce results from both the experimental data and the 3-D model. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.