Carbon nanowall (CNW) films have been prepared by catalytic chemical vapor deposition using only CH4 gas. In the SEM images of the samples prepared at a substrate heating temperature, T-s, of 500 degrees C, the wall structures on the substrates were observed. In those prepared at T-s of 400 degrees C, however, the wall structure was not observed. The electron field emission from the CNW films was observed at small electric field. The wall width and height increased when the Raman intensity ratio, I-D/I-G, decreased. Then, the threshold electric field decreased. The smallest threshold electric field was 2.6 V/mu m in this work. (c) 2005 Elsevier B.V. All rights reserved.