This study addresses a new process for the fabrication of a C/C composite for aeronautic and aerospace industries. The infiltration of a carbon fibrous preform by means of a hydrocarbon in the supercritical fluid state is carried out at high temperature in order to get a carbon matrix. The selected hydrocarbon is methane. The microstructure of the pyrocarbon coating is characterized by optical microscopy, transmission electron microscopy and Raman micro-spectroscopy. The experimental parameters (temperature, hydrocarbon pressure, residence time) are tuned in order to improve the carbon matrix yield. The feasibility of a dense composite from a precursor in its supercritical state, reducing the infiltration duration as compared to chemical vapor infiltration (CVI), is demonstrated.