Gold nanoparticles have been generated for the first time within open-cell macrocellular polyHIPE matrices, leading to new hybrid organic-inorganic catalytic supports labelled "Au@polyHIPE". The overall synthesis can be realized with ease, as it is based on the spontaneous nucleation of gold nanoparticles. These new hybrid organic-inorganic materials have then been tested for heterogeneous catalysis, particularly for eosin Y reduction in the presence of NaBH4. In this reductive media the as-synthesized hybrid catalytic supports "Au@polyHIPE" exhibit a good activity. All the kinetic parameters are discussed in term of internal surface (porosity), external surface (shape), temperature and gold loading revealing a first order reaction. (c) 2007 Elsevier Ltd. All rights reserved.