Based on sheath-core bicomponent composite ion-exchange fibers with modified polystyrene and modified polypropylene, composite fibers were further crosslinked and sulfonated with chlorosulfonic acid to produce strongly acidic cation-exchange fibers. The optimal technology of the obtained fibers was examined, and the structures of the fibers were investigated with Fourier transform infrared spectrophotometry, differential scanning calorimetry, and so forth. The properties were measured with chemical titration, filament strength instrumentation, scanning electron microscopy, and so forth. The results showed that cation-exchange fibers with better mechanical properties and a higher exchange capacity were obtained, and they had higher practicability. (c) 2008 Wiley Periodicals, Inc.