Sorption of benzene on nonsubstituted AlPO4-5 occurs on adsorption centers originating from surface heterogeneity and created by structure defects. The metallic heteroatoms present in the framework of substituted AFI-type materials form additional centers able to bind the benzene molecules. This is equal to an increase of heterogeneity in comparison to nonsubstituted AlPO4-5. Sorption capacity of the MeAPO-5 materials depends on both the content of metal and its distribution throughout the crystals. The distribution parameter plays an important role and may even dominate the effect of the number of metallic heterocenters. Some of the equations based on the Polanyi-Dubinin potential theory can be accepted as suitable for characterizing the distribution of the adsorption potential and adsorption energy of the AFI-type molecular sieves. The dependence between the adsorption potential and the metal content may likely be disturbed by inhomogeneous distribution of the heteroatom centers.