Ammonia was synthesized from its elements at atmospheric pressure in a solid state proton (H+)-conducting cell-reactor. Hydrogen was flowing over the anode and was converted into protons that were transported through the solid electrolyte and reached the cathode (palladium) over which nitrogen was passing. At 570 degreesC and atmospheric pressure, greater than 78 percent of the electrochemically supplied hydrogen was converted into ammonia. The thermodynamic requirement for a high-pressure process is eliminated.