Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier-transform infrared (FTIR), X-ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger-like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH-sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was Studied in detail. It was found that the gel fiber exhibited a large swelling in in alkaline solution and contracting in an acid Solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm(2); and pH-sensitivity was reversible. (C) 2008 Wiley Periodicals, Inc.