Nanocomposite (NC) gels based on natural rubber (NR) and styrene butadiene rubber (SBR) were prepared by using a unique latex blending technique. These NC gels were prepared by first blending the water swollen unmodified montmorillonite clay (Na+-MMT) suspension into the respective latices followed by prevulcanization to generate crosslinked nanogels. Use of water assisted fully delaminated Na+-MMT suspension resulted in predominantly exfoliated morphology in the NC gels, as revealed by X-ray diffraction study and transmission electron microscopy. Addition of Na+-MMT significantly improved various physical, mechanical and thermal properties of these NC gels. For example, 6 phr of Na+-MMT loaded NR based NC gels registered 54% and 200% increase in tensile strength and Young's modulus, respectively, corn-pared to the unfilled NR gels. SBR based NC gels also showed similar level of improvement in mechanical properties. Mechanical properties of NC gels prepared using this route were also compared with the NC gels prepared by co-coagulation and conventional curing technique and found to be superior. In the case of dynamic mechanical properties, NC gels showed higher glass transition temperatures along with a concomitant increase in storage moduli, compared to the unfilled gels. These Na+-MMT reinforced NC gels also exhibited markedly improved thermal stability. (c) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 81-90, 2010