This work reports the electrochemical synthesis of ammonia in solid-state cells at 220 degrees C and atmospheric pressure. Composites of CsH2PO4 and SiP2O7 were used as the electrolyte, and Pt/C-loaded carbon paper was employed as the anode. Five kinds of electrode materials, including Pt/C-, Pt-Ru/C-, Ru/C-, Ru- and Ag-Pd-loaded carbon paper, were examined as the cathode. Electrochemical activities of the cathode materials were evaluated by cyclic voltammetry. Both H-2 and steam were used as the hydrogen source. The successful synthesis of ammonia was confirmed using Nessler's solution. When H-2 was used as the hydrogen source, ammonia formation rates higher than 10(-10) mol cm(-2) s(-1) were obtained using Pt/C- or Ru-loaded carbon paper as the cathode. When steam was used as the hydrogen source, ammonia formation rates higher than 10(-11) mol cm(-2) s(-1) were obtained using Pt-Ru/C- or Ru/C- or Ru-loaded carbon paper as the cathode. Ru and Ag-Pd were the most promising noble metal catalysts for electrochemical synthesis of ammonia from N-2 and steam. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.