Hydrogen (H2) is a promising clean energy vector, but its industrial production is primarily based on fossil fuels, leading to high CO2 emissions. Only a small fraction is 'green hydrogen,' produced through water electrolysis using renewable energy. Similarly, ammonia (NH3), crucial for fertilizers and industrial applications, has potential as a carbon-free energy carrier but relies on the energy-intensive Haber-Bosch process. The electrochemical reduction of nitrite (NO2?) to ammonium (NH4?) offers a sustainable alternative but faces challenges in achieving high selectivity and efficiency. Metal complexes based on the ATCUN (Amino-Terminal Copper and Nickel binding) motif have shown potential for H2 and NH3 production. In this context, our project aims at investigate a series of ATCUN-based metal complexes (M-ATCUN) to design homogeneous electrocatalysts for H2 and NH3 production, active in aqueous solutions with optimal performance. Our strategy is based on the use of water-soluble peptide or pseudopeptide scaffolds that can be adequately modulated to isolate series of well-defined metal complexes. From a structure/activity relationship study combined with a mechanistic investigation, we attempt to rationalize the key parameters for optimal activity.