Thermoplastic polymer based nanocomposites have emerged as new class of materials and numerous related research have been done for the past two decades. The benefits of these materials are light weight, high stiffness and good heat resistance. This paper presents tensile and flexural properties of a polypropylene with a dispersion of modified layered silicates in the polymer matrix. Organo layered silicates were successfully synthesized from Pacitan clay using a cetyltrimethylamonium bromide as a cation exchange agent. Pacitan clay - polypropylene nanocomposites were successfully prepared by a melt intercalation method. The mixture of polypropylene and Pacitan organo clay was added with a maleic anhydride as a modifier and diphenylamine as an initiator in the melting process. The basal spacing of the Pacitan organo clay increased significantly compared to the natural one. Different loadings of Pacitan organo clay in the polypropylene were then analyzed. X-rays diffraction and transmission electron microscope results demonstrated a pattern of clay morphology typically found in polypropylene based nanocomposites. These findings confirmed that intercalated structures were found in the materials. Furthermore, an improvement was observed in the tensile and flexural moduli, while the values of the tensile and flexural strength decreased with the presence of Pacitan organo clay.