Operation of an electrochemical reactor (ECR) for hydrogen production from steam based on the membrane having mixed oxygen ion and electronic conductivity has been considered. On the basis of the described model, one can obtain the dependence of the ECR productivity on the anode and cathode gases parameters as well as the distributions of EMF, membrane conductivity and current density over the electrochemical section of the ECR. The results for the ECR based on the CaTi0.8Fe0.2Oy membrane are presented. (C) 2000 Elsevier Science B.V. All rights reserved.