We straightforwardly synthesized nine different types of ruthenium nanoparticles by using a series of ruthenium metal precursors and ionic liquids. All the materials went for XRD, XPS and SAXS analysis, before going to CO2 hydrogenation reaction as catalyst. As per the results, it was clear that the coordination between anions of ionic liquids and ruthenium nanoparticles played an important role with respect to their catalytic performance in CO2 hydrogenation reaction. Surprisingly, less coordinated and large [DAMI][TfO] mediated ruthenium nanoparticles gave better results over other developed catalytic systems. Narrow size well distributed and stable insitu generated ruthenium nanoparticles were synthesized and found highly active in terms of formic acid formed during the CO2 hydrogenation reaction to other ionic liquid immobilized standing ruthenium nanoparticles. Low catalyst loading, ligand free approach, simple reaction protocol, easy product isolation steps and seven times catalyst recycling are major outcomes of this proposed work.