Polypropylene composites with vapor-grown carbon nanofibers (VGCF's) as reinforcement were prepared. The fibers used have an rage diameter of 200 nm with interesting thermal, electrical and mechanical properties which make them very promising for engineering applications. Fiber purification and activation of functional groups were conducted, where amorphous carbon particles were successfully removed, achieving, high purity fibers. Sample preparation was performed using conventional plastic processing technologies. Interactions between the fibers and the matrix were analyzed by physical, mechanical and electrical properties of the composite. Thermal physical analysis on the samples showed that the presence of the fibers influenced the morphology and crystallinity of the matrix. The decomposition temperature, as well as the crystallization rate increased with increasing fiber content. The electrical resistivity of the prepared composites decreased 12 orders of magnitude providing a potential composite for ESD applications. The addition of VGCF's showed an increase in stiffness of 350. Melt viscosity values were also increased by the VGCF reinforcement. Dispersion, porosity, and bonding aspects were also analyzed.