Given the borderline position of nanocatalysis between homogeneous and heterogeneous catalysis, nanocatalysts are expected to display original catalytic performances. The understanding of the benefits offered by nanocatalysts requires having well-defined systems to conduct in-depth studies in order to clearly determine the relationships between their structure and reactivity. This implies developing synthesis protocols affording a good control of the nanoparticle characteristics (size, shape, composition, surface chemistry, etc.). Among other methods of nanochemistry in solution, the application of organometallic chemistry concepts gave rise to relevant results for accessing well-controlled metal nanoparticles at the molecular level. This approach also allows tuning the chemical environment at the nanoparticle surface by using different stabilizers such as polymers, ligands, ionic liquids, or even inorganic supports. A particular attention is devoted to studying the influence of anchored ligands at the metal surface on the surface properties of the so-obtained nanocatalysts.