Nanoscience is one of the most important research fields that contributes to a high level of scientific and technological developments. The modification of the polymer chemical structure by grafting new chemical species on the polymer backbone is a very appealing way to give new or improved properties to the resulting materials. Inorganic-organic hybrid materials which combines an organic polymer with inorganic species through weak interactions (ionic, hydrogen bonds or Van der Waals interactions) or chemical bonds (covalent, ion-covalent, etc.) have attracted interests. The hybrid materials have unique advantages by bridging the properties between inorganic materials (rigidity, high thermal stability and unique optical, electronic or magnetic properties) and organic polymers (flexibility, dielectric or ductility). The organic-inorganic hybrid copolymer was obtained by the incorporation of polyhedral oligomeric silsesquioxanes (POSS) into the hard segments (polystyrene) in the thermoplastic elastomer of poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS). The hard segment of the polymer was chloromethylated followed by a nucleophile substitution reaction with the amine groups in the POSS. SEBS-g-POSS, polypropylene and oil plasticizer (TPE) was melt mixed in a Haake Rheomix 600 at 180 °C and 100 rpm for 10 minutes using roller rotors. The morphology, evaluated by transmission electron microscopy, did not show phase segregation in SEBS. It could be clearly seen self-aggregated parts originated from the POSS well dispersed in the SEBS matrix. The thermogravimetric analysis showed a small increase in the degradation temperature of TPE using SEBS-g-POSS due the inorganic structure of the POSS. A slight increase in the mechanical properties was observed.