The aim of this work is to study the properties of systems based on polypropylene (PP) and commercial organophilic montmorillonite, prepared by melt intercalation. Because of the non polar character of PP, the polypropylene-graft-maleic anhydride (PP-g-MA) was used as compatibilizer. Materials containing 2.5, 5, 7.5 and 10% of clay and PP, and two extra compositions containing only PP and 15 and 30% of PP-g-MA were processed using a twin-screw extruder. The level of clay dispersion was characterized by X ray diffraction, showing exfoliated/intercalated structures for different concentrations of clay. The crystallization behavior was studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) with hot stage. Tensile properties were also studied and presented a moderate improvement with increase in clay concentration.