Cationic dyeable poly(ethylene terephthalate) (CD-PET) was formed by copolymerizing dimethylterephthalate (DMT),5-sodium sulfonate dimethyl isophthalate (SIPM) with a molar ratio of 2% and ethylene glycol (EG). Blends of regular poly(ethylene terephthalate) (PET) and CD-PET were spun into hollow fibers. The fibers were then treated with aqueous NaOH. This study investigated the physical properties of PET/CD-PET polyblend hollow fibers and their kinetic behavior of alkaline hydrolysis using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), the density gradient method, a gel permeation chromatograph (GPC), a rheometer, and regression analysis of the statistical method. For the alkaline hydrolysis kinetics equation of PET, CD-PET, and PET/CD-PET polyblend materials: Ϫ dW/dt ϭ KC ␣ A ␤ , ␤ values of chip and POY/ FOY hollow fibers are equal to 1. Moreover, R 2 of the kinetics equation of chip/POY/FOY for a from 1.09 -1.35/ 1.08 -1.32/1.06 -1.29 were better than those of a ϭ 1. Experimental results indicate that the rate constant of alkaline hydrolysis was CD-PET hollow fiber Ͼ PET/CD-PET polyblend hollow fibers Ͼ PET hollow fiber and FOY Ͼ POY Ͼ Ͼ Chip.