Pyrochlore-type complex oxides of La1.9Ca0.1Zr2O6.95 were prepared by sol-gel method and characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the sintered complex oxides as solid electrolyte, ammonia was synthesized from nitrogen and hydrogen at atmospheric pressure in the solid state proton conducting cell reactor by electrochemical methods. The rate of evolution of ammonia is up to 2.0 x 10(-9) mol s(-1) cm(-1). (C) 2004 Elsevier B.V. All rights reserved.