This work contain the synthesis, characterization, stabilization and functionalization of different transition Metal Nanoparticles (M-NPs; with M = Cr, Mo, W, Fe, Ru, Os, Co, Rh, Ir, Ag & Au) in Ionic Liquids (ILs). The ILs act as non-surfactant, or weakly coordinating supramolecular network for the kinetic stabilization of the M-NPs. The size of different transitions M-NPs was shown to depend upon the choice of the IL (especially the anion therein), which was demonstrated using different methods and synthesis procedures. Characterization of the dispersed transitions nanoparticles was done by TEM/HRTEM, TED, XRPD, and DLS. Furthermore, NMR spectroscopy and Density Functional Theory (DFT) calculations were done to understand the interactions and stabilization mechanisms of dispersed transition M-NPs in ILs. The DFT calculations and dynamic NMR studies support strongly IL/anion···Au-NPs interactions and a dynamic anion stabilization around M-NP clusters. This mechanistic understanding was crucial for a deep insight into the interaction processes between the IL-network and the "naked" metal nanoclusters.