The distribution of occupied surface coverage after a TAP one-pulse experiment with an irreversible adsorption process in spherical porous catalyst pellets was theoretically analyzed. Analytical expressions for the surface coverage for different reactor configurations, i.e., one-zone and three-zone reactors were determined. It was found that the intraparticle profiles of the surface coverage have the same shape for all catalyst pellets at different reactor axial coordinates. The analytical expression for describing the intraparticle profile of the surface coverage divided by the surface coverage at the pellet outermost is a function of the Thiele modulus and is the same for both reactor configurations. This explains the applicability of the effectiveness factor to calculate the gas conversion for the first order irreversible adsorption/reaction in TAP transient conditions. In addition, for each reactor configuration, the shape of all the profiles of the surface coverage along the reactor axial coordinate for different pellet radial coordinates is the same and is a function of gas conversion. The shape of the interparticle profile of the surface coverage is also the same as that in the non-porous case for the same gas conversion. (C) 2009 Elsevier Ltd. All rights reserved.