NOVELTY - Hollow fiber comprises a hollow positioned at the center of the hollow fiber, macropores positioned at adjacent to the hollow, and mesopores and picopores positioned at adjacent to macropores, where the picopores are three dimensionally connected to each other to form a three dimensional network structure, the hollow fiber comprises a polymer derived from polyimide, and the polyimide comprises a repeating unit obtained from aromatic diamine including at least one ortho-positioned functional group with respect to an amine group and dianhydride.    USE - The hollow fiber is useful for separating at least one gas comprising helium, hydrogen, nitrogen, methane, oxygen and/or carbon dioxide (claimed).    ADVANTAGE - The hollow fiber has oxygen/nitrogen selectivity of greater than or equal to 4 (preferably 4-20), carbon dioxide/methane selectivity of greater than or equal to 30 (preferably 30-80), hydrogen/nitrogen selectivity of greater than or equal to 30 (preferably 30-80), hydrogen/methane selectivity of greater than or equal to 50 (preferably 50-90), carbon dioxide/nitrogen selectivity of greater than or equal to 20 (preferably 20-50), and helium/nitrogen selectivity of greater than or equal to 40 (preferably 40-120). The hollow fiber has excellent gas permeability, selectivity, mechanical strength, and chemical stability, and good endurance to stringent condition such as long operation time, acidic conditions, and high humidity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a dope solution composition for forming a hollow fiber comprising: polyimide including a repeating unit prepared from aromatic diamine including at least one ortho-positioned functional group and dianhydride; an organic solvent; and an additive, where the organic solvent is dimethylsulfoxide, N-methyl-2-pyrrolidone, N-methylpyrrolidone, N,N-dimethyl formamide, N,N-dimethyl acetamide and/or ketone comprising 7-butyrolactone, cyclohexanone, 3-hexanone, 3-heptanone or 3-octanone; and the additive is water, alcohols (comprising methanol, ethanol, 2-methyl-1-butanol, 2-methyl-2-butanol, glycerol, ethylene glycol, diethylene glycol or propylene glycol), ketones (comprising acetone or methyl ethyl ketone), polymer compounds (comprising polyvinyl alcohol, polyacrylic acid, polyacryl amide, polyethylene glycol, polypropylene glycol, chitosan, chitin, dextran or polyvinylpyrrolidone), salts (comprising lithium chloride, sodium chloride, calcium chloride, lithium acetate, sodium sulfate or sodium hydroxide), tetrahydrofuran and/or trichloroethane; and    (2) a method of preparing the hollow fiber, comprising spinning the dope solution composition for forming a hollow fiber to prepare a polyimide hollow fiber; and heat-treating the polyimide hollow fiber to obtain the hollow fiber including thermally rearranged polymer.