Isothermal crystallization of poly(vinylidene fluoride), PVDF, was studied in the presence of montmorillonite, MMT, fillers by polarization optical microscopy, POM. The spherulite growth was monitored as a function of time for different crystallization temperatures and the crystallization kinetics was evaluated with the help of the Avrami theory. The incorporation of MMT fillers is responsible for a reduction of the crystallization time of the polymer based on an increase of the nucleation and a reduction of the spherulite growth rate, the nucleation effect dominating therefore the overall crystallization kinetics. The slowing of the spherulitic growth rate by the presence of the clays due to the clay-polymer interactions is responsible for development of the gamma crystalline phase of PVDF in the composites. (C) 2013 Elsevier B.V. All rights reserved.