The morphology, microhardness, and electrical properties of composites consisting of conductive polypyrrole (PPy) dispersed into a nonconductive polypropylene matrix (PP) as pure component or in form of a sodium montmorillonite/PPy (MMT/PPy) composite have been studied. For comparison, also PP/MMT composites were studied. All types of composites were processed by compression molding or by melt mixing followed by compression molding into plates, which were used for characterization. Scanning electron microscopy and transmission electron microscopy was used to examine the morphology of the prepared materials. The investigation of electrical and dielectric properties was done by dielectric relaxation spectroscopy in a wide frequency range and was related to the composite composition and processing method. The analysis of the conductivity as a function of temperature indicated that the charge transfer mechanism could be described by the variable range hopping model in three dimensions. The microhardness of PP/MMT/PPy composites with different content of MMT or PPy was determined and the creep rate has been estimated. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 407-423, 2009