Tantalum nitride (TaN(x)) films are usually used as barriers to the diffusion of copper in the substrate for electronic devices. In the present work, the TaN(x) coating plays an extra role in the iron catalyzed chemical vapor deposition production of carbon nanotubes (CNT). The CNTs were grown at 850 degrees C on TaN(x) films prepared by radio frequency magnetron sputtering. The correlation between the CNT morphology and growth rate, and the pristine TaN(x) film nature, is investigated by comparing the evolution of the nano-composition, roughness and nano-crystallinity of the TaN(x) films both after annealing and CVD at 850 degrees C.