In this work, the effect of structural characteristics of organomodified clays on the dispersion degree, mechanical and rheological properties of the nanocomposites PP-EP/EVA/nanoclay has been studied. The studied effects were: degree of chemical modification of the clay, length of substitute groups on the surfactant, and the steric effect caused by surfactant structure. The characterization techniques used were Wide Angle X-ray Diffraction (WAXD), Scanning Transmission Electron Microscopy (STEM), Dynamic Mechanical Analysis (DMA), Tensile Test and Capillary Rheometry. Cloisite 6A, 15A and 20A were used to evaluate the first effect. Better intercalation-exfoliation and mechanical properties were obtained when the clay with lower content of surfactant was used (C20A), these results were attributed to a higher saturation of the system. In order to study the second effect, Cloisite 20A and Cloisite 25A were employed. It was found that the bigger initial intergallery space between these nanoclay’s caused by the longer chains in Cloisite 20A, allows the formation of a structure with better intercalated-exfoliated structure. This was confirmed with the observed increase in mechanical properties. Finally, the third effect was studied with Cloisite 10A and 15A. It was clearly seen that only with Cloisite 15A was possible to obtain an intercalated-exfoliated structure. This was attributed to a major steric effect when using C10A than with 15A.