From our prior work and literature reports on Li mediated NH3 synthesis, we observe that with increase in N2 pressure there is an improvement in the NH3 Faradaic efficiency (FE). 9, 10 Beyond a certain pressure there is no improvement in the NH3 FE as we would be in the N2 limited regime. There exists an opUmal concentraUon of the proton donor which balances the Li3N protolysis and Li protolysis steps. Hence for Ca mediated NH3 synthesis, we decided to operate the reactor at a N2 pressure of 50 bar. Ethanol (EtOH) was used as the proton donor at a concentraUon of 0.65 M. The reacUon was carried out in a modified autoclave setup to withstand high pressures. Ni foam was used as the cathode and Pt was used as the anode in a membraneless setup and the electrolyte was sUrred at 700 rpm. Commonly THF is used as the aproUc solvent to dissolve the Li salts in Li mediated NH3 synthesis. One of the challenges in Ca mediated NH3 synthesis is to have a suitable Ca salt that can be dissolved in an aproUc solvent. Calicum salts generally have poor solubility in water and mostly insoluble in non aqueous solvents. The Ca salts that are soluble in water generally exists in its hydrated form as they are hygroscopic. Among the tested Ca salts, CaCl2 has a good solubility in dimethyl sulfoxide (DMSO). 1 M CaCl2 dissolved in DMSO containing 0.65 M EtOH was used as the electrolyte. Switching current approach was used as that provides enhanced stability of the solid electrolyte interface (SEI). A total current density of -5 mA/cm 2 was applied for a period of 2 mins (working phase -where electrodeposiUon of Ca occurs on the electrode) and then switched to 0 mA/cm 2 for a period of 2 mins (resUng phasewhere the electrodeposited Ca reacts with N2 to form Ca3N2 which then reacts with the EtOH to form NH3). Figure denotes the representaUve ChronopotenUometry profile denoUng the applied current densiUes, total cell potenUal, and the charge passed through the system. A total charge of 42 C was applied. The NH3 was quanUfied using the method of standard additons. An NH3 FE of 15.05 ± 2.50 % was obtained from the Ca mediated NH3 synthesis. The reacUon was performed for a period of 4 h and the system becomes unstable beyond that period. The total cell potenUal increases as the reacUon proceeds due to the uncontrolled deposiUon of Ca and instability of the SEI. SEM, XPS, XRD, and EDX are performed on the Ni foam pre and post electrolysis to study the nature of the deposiUon. The work presented in this leYer serves as a proof of concept for Ca mediated NH3 synthesis and this is the first ever reported work. A maximum NH3 FE of 15.05 ± 2.50 % was obtained at -5 mA/cm 2 . The process suffers from several challenges that need to be overcome. Calcium salts are insoluble in most of the solvents. A high throughput screening of the solubility of different Ca salts in different aproUc solvents would enable tesUng different salt and electrolyte configuraUons for the Ca mediated NH3 synthesis and get an opUmal configuraUon to get a maximum NH3 FE. This would enable lowering the total cell potenUal of the system. The role of SEI in determining the NH3 FE is not understood and in-situ studies to probe the SEI is required. The presented work would enable future studies on the NH3 synthesis by using Ca as a mediator.