Abstract: A subject-matter of the invention is a novel process for the preparation of sulphur-modified monolithic porous carbon-based materials by impregnation with a strong sulphur-based acid, the materials capable of being obtained according to this process and the use of these materials with improved supercapacitance properties to produce electrodes intended for energy storage systems. Electrodes composed of sulphur-modified monolithic porous carbon-based materials according to the invention and lithium batteries and supercapacitors having such electrodes also form part of the invention.