Microcellular polymer, known as polyHIPE, which is synthesized by polymerization of high internal phase emulsion, has been associated with heterogeneous nucleation. In this issue, we have generated palladium nanoparticles in situ by an impregnation-reduction method. The nanoparticle synthesis is very sensitive to conditions such as temperature, pH, metallic precursor, solvent, and surface chemistry of the support. We have tried to control the particle sizes and dispersion state by a careful choice of the reaction parameters and/or a suitable matrix functionalization. In a catalysis application aspect, we checked the efficiency of our supports via a hydrogenation reaction. Some of our supports offer good activity, even compared to commercial Pd/C, and also a satisfying reusability.