The effect of different nanofillers and compatibilizers (maleic anhydride-grafted-polypropylene and maleic anhydride-grafted-ethylene propylene diene terpolymer rubber) on the morphology, mechanical, mechanodynamical and thermal characteristics of thermoplastic olefins based on polypropylene and ethylene propylene diene terpolymer rubber blends has been analysed. A better affinity with the matrix and a better dispersion of the nanoparticles is observed in rubber rich matrices. Organoclay, such as Cloisite C15A and Cloisite C20A, treated with a non-polar surfactant give rise to intercalated nanocomposites, and the lower the concentration of surfactant (C20A) the most noticeable increase in interlayer spacing and consequently better properties in the nanocomposites. The maleic anhydride-grafted-ethylene propylene diene terpolymer rubber is a better compatibilizer for organo-clay nanocomposites based on rubber rich matrices.