N-heterocyclic carbene-palladium (NHC-Pd) complexes immobilized on similar to 10nm silica nanoparticles were synthesized. Because of the very high surface area and small size, these nanoparticles remain suspended in a variety of solvents with the catalyst sites readily accessible to the reactants. The catalysts showed excellent activity towards Suzuki coupling reaction of different aryl iodides and bromides with phenyl boronic acid using isopropanol: H2O as solvent. They were also effective for Heck coupling. The nano-sized particles can be easily recovered and repeatedly reused without loss of activity. (c) 2006 Elsevier B.V All rights reserved.