Macroporous kaolin is studied as a convenient substrate for adsorption of petroleum heavy ends in relation to feasible upgrading processes. Understanding the parameters that control adsorption of polar molecules over different adsorption media is important for process optimization. In these regards, adsorption kinetics of small molecular mass anilines (<205 g/mol) over macroporous kaolin was studied. The results indicate that the dynamic and levels of adsorption of these molecules is not controlled by differences in molecular size. The nature of substituents on the aniline ring plays an important role on the adsorption. The incorporation of oxygen as a methoxy group in the ortho or para position enhances the adsorption, while the incorporation of alkyl groups has mixed effects on this phenomenon, decreasing the adsorptivity when the group in placed in the ortho position. The presence of two aromatic rings attached to the aniline molecule such as I-amino anthracene increases the adsorption uptake. Moreover, the presence of sulfur in the form of methylthio groups reduces the adsorption particularly when the group is located in the ortho position. Finally, thermodynamics of the adsorption of these anilines over macroporous kaolin are studied and found primarily governed by the type of substituent present on the aromatic ring.