The Pd-o-nanoparticles, generated into the nanopores of modified Montmorillonite clay, were evaluated for catalytic performance for the Suzuki-Miyaura cross coupling reactions. The modification of Montmorillonite clay was carried out by activating with H2SO4 under controlled conditions for generating nanopores on the surface for serving as a 'Host' for the Pd-o-nanoparticles which were prepared in situ by loading of K2PdCl4 through incipient wetness impregnation technique followed by reduction with hydrazine hydrate. The Powder-XRD, SEM-EDX, TEM, N-2 adsorption, XPS, etc. analyses were carried out to characterize the stabilized nanoparticles as well as the support. The TEM study reveals that the evenly distributed Pd -nanoparticles are below 10 nm size and exhibit face centred cubic (fcc) lattice geometry. The supported Pd -nanoparticles exhibit efficient heterogeneous catalytic performance for the Suzuki-Miyaura coupling reactions between different organoboronic acids and aryl halides for preparing the cross-coupling products in 94% isolated yield (maximum) and 100% selectivity in water under ligand free conditions. The nanocatalysts could be recycled at least three consecutive runs with a little loss of their catalytic activities. 2013 Elsevier B.V. All rights reserved.