The electrochemical synthesis of ammonia from N-2 and H+ ions was studied over a Ni-BZCY72 cermet, with and without H-2 in the gas phase. The effect of temperature, cathode chamber feed composition and applied voltage was explored in detail. Without H-2 in the cathode chamber, the highest rate was 1.7 x 10(-9) mol/s.cm(2) at 620 degrees C. When H-2 was present in the gas phase, ammonia was synthesized electrochemically at much higher rates and Faradaic efficiencies. The maximum net electrochemical synthesis rate of 4.1 x 10(-9) mol/s.cm(2) was obtained with P-H2/P-N2 = 1 at 620 degrees C, corresponding to a 140% enhancement of the open circuit rate at the cost of electrical energy. In both cases these high rates were accompanied by a low Faradaic efficiency, pointing to the need for catalyst improvement. (C) 2015 Elsevier B.V. All rights reserved.