Thermoplastic elastomer nanocomposites based on acrylonitrile butadiene rubber (NBR) and poly(ethylene-co-vinyl acetate) (EVA) with different weight ratios (20, 40 and 60 wt% of NBR) and 5 wt% of organocaly (OC) were prepared in an internal mixer. The results obtained from X-ray diffraction and transmission electron microscopy (TEM) micrographs showed that due to the OC–EVA interaction, nearly all of the clay platelets were exfoliated. Scanning electron microscope (SEM) was used to investigate the particle size and phase morphology. SEM images for the unfilled blends revealed a two-phase structure in which the NBR domains were dispersed into the EVA phase. However, for the blend containing 60 wt.% of NBR, a co-continuous morphology was exhibited. The addition of OC decreased the NBR domain size significantly in which NBR remained as a dispersed phase even for the blend having the highest amount of NBR studied. Young's modulus and yield stress increased, but elongation at break and stress at break decreased for the nanocomposites in comparison with that of the unfilled materials. Thermal studies indicated that although OC decreased the degree of crystallinity and crystallization temperature of EVA slightly, it showed no effect on EVA melting temperature in comparison with that of the unfilled samples. It was also found that the nanocomposites behaved as shear thinning fluids over the entire range of angular frequency and the values of storage modulus and stress relaxation modulus of the nanocomposite containing 20 wt% of NBR was even higher than that of the NBR alone.