Nio-nanoparticles of approximately 5nm were generated by incipient wetness impregnation of NiCl2·6H2O 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 10nm size on the surface, which act as a “Host” for Nio-nanoparticles. Powder-XRD, SEM-EDX, HR-TEM, N2 adsorption, XPS, etc. analyses were carried out to characterize the stabilized nanoparticles as well as the supports. TEM study reveals that Nio-nanoparticles of size below 5nm were evenly distributed over the support and exhibit face centred cubic (fcc) lattice. The supported Nio-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.