Process for the production of a carbon/carbon composite material part using mesophase powder

Process for the production of a composite material part having a carbon fibre reinforcement embedded in a carbon matrix, said fibres being continuous, involving the stages of dispersing infusible mesophase microspheres in a solution containing a binder and a solvent able to wet the carbon fibres and thus form an impregnation bath, the binder and the solvent not being carbon precursors, preparing the impregnation bath, impregnating each continuous fibre by said bath, cutting each impregnated fibre into sections, placing the impregnated fibre sections in a mould and unidirectionally pressing said sections in the mould whilst heating them to a first temperature T.sub.1 exceeding ambient temperature and able to evaporate the solvent and the binder and make the mesophase microspheres flow and then to a second temperature T.sub.2 exceeding the first temperature and able to pyrolyze the mesophase microspheres in coke form.