By using a dedicated solvent and an appropriate metal precursor species, it is possible to build stable nanoparticle solutions in a fast and effective way. These solutions can be simply used in chemical reactions directly as a catalyst solution. With different transition metal species and solvents of variable polarity and density, a great number of catalytic reactions can be carried out. The catalyst can easily be recycled and, depending on the selection of the catalytic system, the solutions were stable over months.