Multi-wall Carbon nanotubes are successfully grown on Si (100) substrate in the hot filament chemical vapor deposition system without using the external catalyst. High resolution scanning electron microscopic images of the deposited films show a long noodle shape and vertically grown carbon nanotubes distributed uniformly over a large area of the substrate with relative high growth density. HRTEM studies show that the grown tubes are multi-walled. The diameter of the nanotubes is about 20 nm and the thickness of the grown film is similar to1.2 mum. From XRD and EDAX analyses traces of catalyst materials (Fe, Co, Ni etc.) are not found except tungsten, which might be on the surface of the film. X-ray photoelectron spectroscopy (XPS) indicates that presence of Carbon (C-1s). Micro Raman spectroscopy and HRTEM study reveal that the grown tubes are multi-wall which are partially crystallized. (C) 2004 Kluwer Academic Publishers.