Abstract: A method for measuring the height of a forest of carbon nanotubes, containing: a) providing a substrate having a growth area containing at least one measurement zone containing a growth zone and a sterile zone, the growth zone being defined by a segment of the substrate containing a growth catalyst of the nanotubes, and b) growing catalytically by CVD the forest of nanotubes in the growth zone, wherein, at least in step b) contains: irradiating the measurement zone with an incident light beam; measuring, at various times, the intensity of the beam reflected by the measurement zone; and determining the height of the forest of nanotubes from the reflected-beam intensities measured at the various times.