NOVELTY - A hollow fiber consists of hollow positioned at the center of the fiber, macropores positioned adjacent to the hollow, and mesopores and picopores positioned adjacent to the macropores. The picopores are 3-dimensionally connected to form a 3-dimensional network structure. The fiber consists of polymer derived from polyimide comprising repeating unit obtained from aromatic diamine containing ortho-positioned functional group with respect to amine group and dianhydride.    USE - Hollow fiber used for separating gas chosen from helium, neon, hydrogen, nitrogen, methane, oxygen and/or carbon dioxide (all claimed). Uses include but are not limited to reverse osmosis membrane, ultrafiltration membrane, microfiltration membrane and gas separation membrane.    ADVANTAGE - The hollow fiber has high fractional free volume, excellent gas selectivity, gas permeability, excellent chemical stability, mechanical properties, gas selectivity, and can endure mild conditions, long operation time, acidic conditions and high humidity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) dope solution composition for forming the hollow fiber, which comprises the polyimide, organic solvent chosen from methanol, ethanol, 2-methyl-1-butanol, 2-methyl-2-butanol, ( gamma )-butyrolactone, cyclohexanone, 3-hexanone, 3-heptanone, 3-octanone, acetone and methyl ethyl ketone, tetrahydrofuran, trichloroethane, dimethylsulfoxide, N-methyl-2-pyrrolidone, N,N-dimethylformamide and/or N,N-dimethylacetamide, and additive chosen from water, glycerol, ethylene glycol, propylene glycol, diethylene glycol, polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyethylene glycol, polypropylene glycol, chitosan, chitin, dextran, polyvinylpyrrolidone, lithium chloride, sodium chloride, calcium chloride, lithium acetate, sodium sulfate and/or sodium hydroxide; and    (2) manufacture of the hollow fiber, which involves spinning the dope solution composition to form polyimide hollow fiber, and heating the obtained polyimide fiber to obtain hollow fiber containing thermally rearranged polymer.