The intercalation capability of poly(styrene-b-ethylene butylene-b-styrene) (SEBS) in nanocomposites of isotactic polypropylene (PP) with 5 wt % of organically modified montmorillonite (C20A), prepared by melt blending, has been investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) Studies have shown the presence of intercalated structures in the nanocomposite. In a previous research, we studied the intercalation capability of a commercial compatibilizer.(1) Those results, with the study we present in this work, allow us a better understanding of the mechanism of compatibilization and it deeper characterization of the Structure and morphology of the nanocomposite. scanning transmission X-ray microscopy (STXM) has been used. Because of the excellent chemical sensitivity and the high spatial resolution (similar to 40 nm) of this technique, we have proved that C20A is not in direct contact with the PP phase because the clay is always located inside the elastomer domains. The elastomer is surrounding the nanoclay, hindering the clay exfoliation and preventing its dispersion in the PP matrix. Oil the other hand, we have observed that the presence of the clay caused the SEBS particles to become elongated in shape and retarded the coalescence of the elastomer particles.