Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium clibasic phosphate, oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of the oxidation temperature of the PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN-based activated carbon hollow fiber (PAN-ACHF) were studied. When PAN hollow fibers were oxidized at 270 degrees C, because of drastic oxidation, chain scission occurred, and the number of pores within and on the surface of the resultant PAN-ACHF increased, but the pores were just in the thinner region of the skin of PAN-ACHF. The surface area of PAN-ACHF reached a maximum when the oxidation temperature was 270 degrees C. The adsorption ratios to creatinine were all higher than 90 % at all oxidation temperatures, and the adsorption ratio to VB12 reached a maximum (97 %) at 230 degrees C. The dominant pore sizes of the mesopores in PAN-ACHF ranged from 2 to 5 nm. (c) 2005 Wiley Periodicals, Inc.