Polypropylene (PP)/organomontmorillonite (OMMT) nanocomposites have been successfully prepared by melt intercalation by using the conventional method of twin-screw extrusion and subsequently submitted for melt-spinning. The structure and properties of the PP/clay nanocomposites and hybrid fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and crystallization dynamics, etc. The organoclay layers were found to disperse in the PP resin at the nanometer level. The nanoscaled OMMT layers, dispersed in the PP matrix, actually played the role of heterogeneous nuclei species in the process of PP crystallization and increased the nucleation speed of the composites, hereby leading to the increase of crystallization rate of the as-spun fiber. Meanwhile, it was found that the crystallinity of PP/OMMT hybrid fibers is much higher than that of pure PP fiber at the same draw ratios, whereas the orientation of PP/OMMT hybrid fibers is much lower than that of pure PP fiber at the same draw ratios. Because of the effective intercalation of OMMT into PP matrix, the nanocomposites have good spinnability, and the moisture absorption of the final PP fiber is improved. (C) 2004 Wiley Periodicals, Inc.