This paper reports functionalization of carbon nanotubes (CNTs) via cathodic electropolymerization. Indeed, this technique ensures good control of the grafted polymer (PMAN in our study) on the surface of the substrates (CNTs). The study was done both on single-wall nanotubes (SWNTs) and multi-wall nanotubes (MWNTs) following two distinct approaches: on one hand, the CNTs were dispersed in an organic solution under stirring. This option aims at their functionalization by transient contact with a metallic cathode, but did not give promising results. On the other hand, the CNTs were synthesized (produced) on the surface of an electrode that will be used as cathode in the grafting process. The surface modifications were followed by SEM, XPS, TGA (Thermo Gravimetry Analysis). (c) 2006 Elsevier B.V. All rights reserved.