The Co-filled carbon nanotubes (CNTs) film was produced on silicon substrate by electron cyclotron resonance microwave plasma chemical vapor deposition (ECR-CVD). The effects of different plasma powers of 200, 300, 400 and 500 W, on the morphology, structure and electrical properties of the CNTs film, were studied. The results showed that the surface density of the vertical nanotubes decreased when the plasma power was higher than 200 W. When plasma power of 300 W was used, the ends of the metal-filled carbon nanotubes (MF-CNTs) became straighter and more uniform. The Co-filled CNTs grown at 300 and 400 W had a current discharge at the applied voltages of 30 and 40 V, respectively. In addition, the surface morphology and the structure of the CNTs film were examined using scanning electron microscopy (SEM) and high-resolution field emission gun transmission electron microscopy (TEM). Energy dispersive X-ray spectroscopy (EDXS) analyses were performed to identify the composition of the material inside the CNTs. (C) 2007 Elsevier B.V. All rights reserved.