CNx nanotubes have been generated by thermal decomposition of ferrocene/xylene over cobalt powder at 780℃—940℃ in an atmosphere of N2, H2 and NH3 released from NH4Cl pyrolyzing at 300℃. The high-resolution transmission electron microscope (HRTEM) images show that the tubes consist of unusual “interlinked-cone". The catalytic growth mechanism of CNx nanotubes is discussed based on the formation energy of different structures. Raman spectroscopic studies show that the ID/IG ratio represents the crystallinity of the CNx nanotubes. The shift of the Raman band to higher frequencies confirms the nitrogen incorporation.