A new model of interpretation for the mercury porosimetry experiment has been presented. The void space of a porous solid is modeled by separate representations of both the macroscopic (>10 mu m) and the mesoscopic (<10 mu m) length scale properties of the material. Complementary information from nitrogen adsorption, on the mesoscopic scale, and NMR imaging, on the macroscopic scale, is used in conjunction with the mercury porosimetry data to provide a more accurate structural representation of a porous medium. The model is therefore able to probe spatial geometric changes in pellet structural architecture over many length scales during processes such as catalyst manufacture and the deactivation of catalysts by coke deposition.