Strategies for converting CO2 Valuable products are of the utmost importance in reducing the environmental risks associated with high levels of this greenhouse gas and offer unique opportunities to turn waste into useful products. While nickel-based catalysts are used as a low-earth metal for the sustainable reduction of CO2 are known, the vast majority predominantly produce CO as a product. Here efficient and selective CO2 The reduction to formate as a synthetically valuable product was achieved with new nickel complexes that contain a tailor-made C, O-bidentate chelating mesoionic carbene ligand. This nickel (II) Complexes are easily accessible and show excellent catalytic activity for electrochemical H.+ Reduction to H.2 (from HOAc in MeCN) and CO2 Reduction (of CO2-saturated MeOH / MeCN solution) with high Faraday efficiency, in order to obtain formate exclusively as an industrially and synthetically valuable product from CO2. The most active catalyst precursor has the 4,6-di-tert-Butyl substituted phenolate triazolylidene ligand, tolerates various proton donors including water and achieves an unprecedented Faraday efficiency of 83% for formate production. This is the most active and selective Ni-based system known to date for converting CO2 in formate as an important raw material chemical.