Abstract: The invention relates to a chemical reactor with a nanometric superstructure, comprising at least one member wherein at least one reaction chamber is arranged, and said reaction chamber being filled at least partially with a high specific surface area material having a specific surface area greater than 5 m2/g, and characterized in that said high specific surface area material is selected from nanotubes or nanofibers. These nanotubes or nanofibers are preferably selected in the group consisting of carbon nanofibers or nanotubes, ?-SiC nanofibers or nanotubes, TiO2 nanofibers or nanotubes. They may be deposited on an intermediate structure selected in the group consisting of glass fibers, carbon fibers, SiC foams, carbon foams, alveolar ?-SiC foams, said intermediate structure filling the reaction chamber of said reactor at least partially.