In this article, the surfaces of polypropylene (PP) fibers were grafted by three different grafting systems, of which the initiators belonged to three different types, namely, the water-soluble initiator, the redox initiator, and the oil-soluble initiator, respectively. The grafted products were characterized by FTIR, and the grafting degrees were determined by acid-base titration. In comparison, it was found that the oil-soluble initiator might be more suitable for the surface grafting modification of PP fibers. (c) 2005 Wiley Periodicals, Inc.