In the field of polymer clay nanocomposites, naturally occurring smectite group of clays are the most commonly used nanofillers. In the present work, smectite group clay, hectorite was synthesized in the laboratory with an intention to understand the structure-property relationship of polymer nanocomposites, with special reference to the characteristics of the nanoclays. The nanocomposites were prepared using these synthetic clays and fluoroelastomer by a solution mixing process. The clays and their nanocornposites were characterized by using X-ray diffraction, X-ray fluorescence, infra-red spectroscopy, and transmission electron microscopy. It was observed that clav formation was a function of the concentration of the constituent materials. The gallery spacings and surface areas of synthetic clays are higher than those of the natural clay. Mechanical, dynamic mechanical, swelling, and thermal properties of these nanocomposites were also Studied. The properties of these nanocomposites were compared with the nanocomposites obtained from natural clays, available commercially. Synthetic clay filled samples showed better properties than the natural clay filled samples, e.g., synthetic hectorite filled sample exhibited 75% increment in tensile strength and 24% improvement in 100% modulus compared with the natural hectorite based system. The results were explained with the help of thermodynamics and morphology. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1094-1104, 2009