Sodium montmorillonite (Na-Mt) was modified by cetyltriemethylammoniumbromide (CTAB) through cation exchange technique followed by grafting with 3-aminopropyltriethoxysilane (APT). The effects of organophillic surface treatments of montmorillonite on compatibilization of natural rubber (NR) /acrylonitrile butadiene rubber (NBR) blends was investigated. Physico-mechanical properties of rubber nanocomposites compatibilized with organomodified montmorillonite revealed strong nanocomposite with high tensile properties, impact strength and good resistance to flex fatigue, abrasion and compression set. Dynamic mechanical thermal analysis (DMTA) revealed a marked increase in storage modulus (E') and lesser damping characteristics of organically modified clay mineral polymer nanocomposites (CPN) due to intercalation of organophilic montmorillonite by rubber matrix. The morphology of the blends became homogeneous and smoother with the presence of exofoliated/intercalated organically modified montmorillonite. Organomodified layered silicate sheets of montmorillonite greatly enhanced barrier properties by creating tortuous path that retarded the progress of solvent molecules through rubber matrix.