Ni-o-nanoparticles of approximately 5 nm were generated by incipient wetness impregnation of NiCl2 center dot 6H(2)O into the nanopores of the acid activated montmorillonite (AT-Mont) followed by reduction with hydrazine hydrate. The modification of montmorillonite was carried out by activating with H2SO4 under controlled conditions for generating nanopores up to about 10 nm size on the surface, which act as a "Host" for Ni-o-nanoparticles. Powder-XRD, SEM-EDX, HR-TEM, N-2 adsorption, XPS, etc. analyses were carried out to characterize the stabilized nanoparticles as well as the supports. TEM study reveals that Ni-o-nanoparticles of size below 5 nm were evenly distributed over the support and exhibit face centred cubic (fcc) lattice. The supported Ni-o-nanoparticles serve as efficient and selective heterogeneous catalyst for hydrogenation of halonitrobenzene (HNB) to corresponding haloaniline (HAN) with conversion 78-100% and selectivity 96-99.4%. The metal nanocatalysts could be recycled and reused several times without significant loss of their catalytic activities. (c) 2014 Elsevier B.V. All rights reserved.