The synthesis of polynorbornene by ring opening metathesis polymerization (ROMP) in the presence of 1 2 nd generation Grubbs catalyst-functionalized nanotubes, is reported. A characterization of the 2 nd generation Grubbs catalystfunctionalized nanotubes was performed by TGA (Thermogravimetric Analysis) on-line connected with a quadrupole-mass spectrometer, in order to quantify the amount of catalyst grafted to the nanotube surface. The activities of the catalyst-functionalized nanotubes in ROMP of 2-norbornene were compared with those of pure 2 nd generation Grubbs catalysts.