The properties of polypropylene composites can be tailored through the use of nanoclay fillers. The effectiveness of a metallocene-catalyzed hydroxyl-functional polypropylene in the compatibilization of polypropylene layered nanosilicate composites was studied, and the results were compared with those for a commercial maleic anhydride functionalized polypropylene. Polypropylene/organoclay nanocomposites were prepared by melt blending, and two polypropylene/compatibilizer/organoclay ratios, 90/5/5 and 70/20/10, were characterized. The organomodification of the clay was carried out with octadecylamine and N-methylundecenylamine. The structure of the layered silicate was studied by transmission electron microscopy, wide-angle X-ray scattering, and small-angle X-ray scattering. The fracture surfaces of the composites and thus the efficiency of the compatibilizers to penetrate the galleries of the organo-clays were characterized by scanning electron microscopy, and the melt viscosity was studied by stress-controlled rotational rheometry. The nanostructure was observed with both alkyl amines used for intercalation. The fillers facilitated the processability of all the composites, consisting of equal amounts of compatibilizer and organoclay filler and, in some of the composites, containing twice as much compatibilizer as organoclay filler. (c) 2005 Wiley Periodicals, Inc.