Vertically aligned single-walled carbon nanotube films up to 5 mum thick were produced by an alcohol CVD process, in which hydrogen was supplied during the heating-up stage only. A time-progressive investigation of the growth process was performed based on FE-SEM images of SWNT films grown for different CVD times. Measurements of the film thickness by SEM and optical absorbance showed a non-linear growth rate. In situ monitoring of the SWNT film thickness was achieved by measuring the intensity of laser light passing through the sample, and using the relationship between light absorbance and film. thickness. (C) 2005 Elsevier B.V. All rights reserved.