Due to a high number of possible applications in various domains, metal nanoparticles are nowadays the subject of an extensive development. This interest in metal nanoparticles is related to their electronic properties at the frontier between those of molecular species and bulk compounds which are induced by their nanometric size. Regarding the field of catalysis, the growing attention for metal nanoparticles also results from the high proportion of surface atoms present in the upper layer of the metallic core which gives rise to numerous potential active sites. Thus, nanocatalysis (which involves the use of catalysts with at least one dimension at the nanoscale) has emerged in the field of modern catalysis as a domain on the borderline between homogeneous and heterogeneous catalysis. Present developments aim at multifunctionality which can be achieved by the proper design of complex nanostructures also named nanohybrids. In nanohybrid the term “hybrid” refers to the appropriate association between a metal core and a stabilizing shell such as a polymer, a ligand, an ionic liquid, or even a support (inorganic materials, carbon black, carbon nanotubes, etc.…). This association can be considered as crucial to tune the surface properties of nanostructures and consequently their catalytic performance. The main expectation for the scientific community is that precisely designed nanoparticles (in terms of size, shape, and composition including surface ligands) should offer the benefits of both homogeneous and heterogeneous catalysts, namely high efficiency and better selectivity.