Well-aligned multiwalled nanotubes (MWNTs) have been deposited by plasma-enhanced chemical vapor deposition of acetylene (C2H2) on nickel-coated quartz glass at 650 degreesC. The growth reaction of the carbon nanotubes was found to be dependent on the morphology of the metal catalyst, which was related to the thickness of the Ni catalyst film. The flow rate of the hydrocarbon gases was observed to be crucial for the growth of high density carbon nanotubes. Well-aligned and dense carbon nanotubes were grown uniformly on 15-nm thick Ni film with a flow rate of 15 and 30 seem for C2H2 and NH3, respectively. Transmission electron microscopy confirmed the structures to be hollow with Ni particles encapsulated by the multi-walls at the tip of the nanotube.