The blend of polypropylene (PP) and atactic polystyrene (PS) hybrid with nano-ceria (CeO2) was prepared for fine dyeable fiber. Nano-CeO2 modified with stearic acid was in situ added to PS by radical suspension polymerization. The dispersion of hy-PS with nano-CeO2 in the PP crystals was investigated. The rheological behavior of the blend was similar to that of PP under the testing conditions, and the blend had stable spinning and drawing processability. The fine modified PP filaments were processed from the blend and had practical mechanical properties. The dyeability of the knitting fabrics from these filaments was studied. The increased amorphous content and the interface between PP and hy-PS allowed the dye to penetrate the fiber, and the modified PP fiber had strong affinity to dye because of the complexation between cerium and dye. These effects resulted in improving K/S value and color fastness to soaping. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1953-1958, 2009