Nanocomposites based on fluoroelastomer and modified and unmodified sodium montmorillonite clays were prepared. Dynamic mechanical thermal analysis was performed on these nanocomposites over a range of temperatures (-60 to +60 degrees C), frequencies (0.032-32 Hz), and strains (0.002%-2%). The results showed that there were significant changes in the glass transition temperature and storage modulus with the addition of small amount (4 phr) of the modified and the unmodified nanofillers. The tan 6 peak heights decreased and the storage modulus increased in general, but it was more prominent in the case of the unmodified clay. With the addition of the nanoclays, the cross-over point in the double logarithmic plot of storage modulus (E') and complex viscosity (eta*) with frequency, shifted toward higher frequency. Interestingly, with increasing strain, the nanocomposites demonstrated a sudden upturn in the storage modulus after similar to 0.2% strain amplitude, because of the formation of alpha-crystallization in the elastomer structure. The uniaxial strain before strain sweep experiment increased the storage modulus remarkably. The results were explained with the help of X-ray diffraction and transmission electron microscopy.