The dynamics of countercurrent transport of binary and ternary gas mixtures, containing one absorbable gas, through a porous medium accompanied by a spontaneous temporary build-up of pressure inside the pores was experimentally studied. Attempts to simulate the pressure responses based on Maxwell-Stefan constitutive equation (2) were made with the conclusion that adsorption in equilibrium overpredicts the temporal pressure inside the porous solid. To simulate acceptably pressure responses for the porous catalyst ICI-52/1 adsorption kinetics must be considered.