Nanoparticles immobilized on a solid support are able to catalyse a wide range of reactions, and they offer advantages in the recycling and manipulation compared to homogeneous catalyst. In the present work, Preparation of such materials is described, and then their use in catalysis is checked. As support, we have chosen a microcellular polymer, known as polyHIPE, which is synthetised by polymerisation of high internal phase emulsion. As reactive part of the catalyst, we have generated palladium nanoparticles in-situ by an impregnation-reduction method. We have synthetised a wide range of Palladium/PolyHIPEs hybrid materials upon differents conditions and characterised them by techniques such as SEM, TEM, XPS and infra-red spectroscopy. We have tried to control particle sizes and dispersion state by a careful choice of the reactions parameters and/or a suitable matrix fonctionnalisation. To check the efficiency of our supports in catalysis, we have chosen a test reaction which is the Suzuki coupling reactions. We have found a strong dependance of the activity with the particles stabilization strenght, but also with the surface chemistry of the colloïds. Some of our supports offer a good activity, even compared to commercial and soluble catalysts, and also a satisfying reusability and selectivity. Those reactions have been extended to the less reactive non activated aryl chloride.