TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The starting material comprises benzene, ethylbenzene, butyl benzene, toluene, xylene, styrene, biphenyl, phenyl acetylene, phenol, ethyl phenol, fluoranthene, pyrene, chrysene, phenanthrene, anthracene, naphthalene, methylnaphthalene, fluorene, acenaphthene, pitch, pitch coke, petroleum coke and coal tar.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The fluid is chosen from the aromatic compound of starting material, solvent for the aromatic compound, solvent for the catalyst, water, dinitrogen monoxide and ammonia. The solvent for the aromatic compound or catalyst comprises carbon dioxide, alcohols, water and ethers. An inert gas chosen from argon, helium and nitrogen, is added to the reaction system.Preferred Catalyst: The catalyst comprises a transition metal and/or a transition metal compound. The transition metal is nickel, cobalt, iron, copper, chromium, tungsten, molybdenum, titanium, ruthenium, rhodium, palladium and silver. The transition metal compound is chosen from metal sulfides, transition metal carbides, organo transition metal compounds, transition metal nitrides, transition metal oxides and transition metal salts. The transition metal sulfide is chosen from nickel sulfide, iron sulfide, cobalt sulfide, copper sulfide, titanium sulfide, tungsten sulfide and molybdenum sulfide. The transition metal carbide is chosen from tungsten carbide, molybdenum carbide and titanium carbide. The catalyst comprises an organo transition metal compound consisting of ferrocene, nickelocene, nickel formate, nickel oxalate, nickel naphthenate, nickel phthalocyanine, cobalt phthalocyanine, copper phthalocyanine, nickel acetyl acetonato, cobalt acetyl acetonato, iron acetyl acetonato, copper acetyl acetonato, nickel carbonyl, cobalt carbonyl, iron carbonyl, bis(triphenyl phosphine)dicarbonyl nickel, dibromo bis(triphenyl phosphine)nickel, and/or chloro tris(triphenylphosphine)rhodium.A surface-active agent is made to coexist with the transition metal element containing catalyst.Preferred Properties: The nanocarbon materials comprise several microunits of worm-like form, filament form, rod-like form comprising spherical microparticles aggregated into a unit, coral-like form and tube-like form, observed from an electron microscope image. The microunits have an average diameter of 2-400 nm. Preferably, the nanocarbon materials comprise an aggregate of several tube-like nanocarbons having an average diameter of 0.4-400 nm, which are aggregated, observed from transmission electron microscope image. The microunits have an average length of 100-10000 nm. The nanocarbon materials have a transition metal element, transition metal oxide, transition metal carbide or transition metal sulfide inside the material or at the tip portion.Preferred Process: The method further involves subjecting the reaction product to a heat treatment at 400-2800 degreesC. Heat-treating step is conducted at 600-2200 degreesC, in a gas atmosphere of argon, helium and/or nitrogen. The method includes a purification step by magnetic force using a permanent magnet or an electromagnet. EXAMPLE - Toluene (2.5 g) as starting material was mixed with nickelocene (bis(cyclopentadienyl)nickel) as transition metal element containing catalyst (0.2 g). Dry ice as supercritical or subcritical fluid (30 g) was added to the mixture and reaction was performed, at 450 degreesC under a pressure of 12 MPa for 6 hours, to obtain a powdery nanocarbon product (0.4 g). The product comprised enormous number of worm-like microunits of average diameter 20-30 nm and average length 200-500 nm. The product comprised nickel metal microparticles in the tip portion. The nanocarbon product had a purity of nearly 100%, and had excellent hydrogen storing ability.