Nanocomposites of isotactic polypropylene (iPP) and carbon nanoparticles (CN) were prepared using a twin-screw co-rotating extruder. Morphological characterization of the prepared materials was carried out by TEM and confocal micro-Raman. Viscoelastic and thermal properties were also determined by DMA and DSC measurements. Storage modulus was improved while the T. was slightly increased. A small increase of melting temperature was obtained while crystallization temperatures were slightly altered. Degradation kinetics was investigated by thermogravimetric analysis (TGA and DTG). The nanoparticles' presence caused a shift of the onset mass loss temperature to higher temperatures. The activation energies were calculated using the isoconversional methods of Ozawa, Flynn and Wall (OFW) and Friedman and were found to be significantly enhanced by the presence of carbon black nanoparticles. Degradation took place in two autocatalysis stages, the first corresponding to a small initial mass loss, while the second, where substantial mass loss took place, was attributed to the main decomposition mechanism. (C) 2007 Elsevier B.V. All rights reserved.