A subject of the present invention is a process for producing carbon nanotubes, the process comprising: a) the synthesis of alcohol(s) by fermentation of at least one vegetable matter and optionally the purification of the product obtained; b) the dehydration of the alcohol or alcohols obtained in a) in order to produce, in a first reactor, a mixture of alkene(s) and water and optionally the purification of the product obtained; c) the introduction, in particular the introduction into a fluidized bed, in a second reactor, of a powdery catalyst at a temperature ranging from 450 to 850° C., this catalyst comprising at least one catalytic metal supported by an inert solid substrate, the grains of catalyst having a d50 of less than 300 μm; d) bringing the alkene produced in b) into contact with the powdery catalyst of stage c), optionally in a fluidized bed, in order to form carbon nanotubes and hydrogen on the surface of said catalyst by catalytic decomposition of said alkene; e) the recovery of the carbon nanotubes produced in d). The invention also relates to nanotubes capable of being obtained according to the abovementioned process, which can be advantageously used in all the known fields of application of carbon nanotubes.