The purpose of the project is to develop a new surface tr eatment for carbon fibres by: - plasma polymerziation of a monomer in gaseous phase on the fibre under the effect of a cold plasma; - electropolymerization based on polymerization of a monomer in an electrolytic bath. The development of improved or new carbon fibre based composite materials calls for new surface treatment techniques. Among these, deposition of a polymeric interphase between the reinforcement and the interface matrix is an attractive solution. This treatment should provide a greater degree of flexibility in the optimization of the fibre-matrix interface. It should also provide good resistance to the formation and propagation of microcracks for which present composite materials are sensitive. The deposition of a polymeric interphase is thus an important process in the interface production of high performance composite structures.