Nanocomposites based on poly(propylene) and multi-wall carbon nanotubes (up to 2 vol.-%) were melt blended, yielding a good dispersion of nanotubes without using any organic treatment or additional additives. Carbon nanotubes are found to significantly enhance the thermal stability of poly(propylene) in nitrogen at high temperatures. Specifically, the nanotube additive greatly reduced the heat release rate of poly(propylene). They are found to be at least as effective a flame-retardant as clay/poly(propylene) nanocomposites.