A cellulosic ion exchange fiber (CIEF) was prepared by using room-temperature ionic liquid 1-(3-chloro-2-hydroxypropyl)-3-methylimidazolium chloride as reaction reagent and medium. The results showed the degree of substitution of the CIEF was up to 0.78. The product was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, scanning electronic microscope. The thermal stability of the CIEF was over 200°C. The adsorption experiments of CIEF for Cr(VI) were performed. The adsorption capacity of CIEF for Cr(VI) was found to be 196.1 mg g−1 at 30°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.