The water gas shift (WGS) reaction was studied in a double-chamber high temperature proton conducting cell (HTPC). The proton conductor was a strontia-ceria-ytterbia (SCY) disk of the form: SrCe0.95Yb0.05O3-alpha and the working electrode was a polycrystalline Fe film. The reaction temperature and the inlet partial pressure of CO varied between 823 and 973 K, and between 1.0 and 10.6 kPa, respectively. The inlet partial pressure of steam (P-H2O) was kept constant at 2.3 kPa. An increase in the production of H-2 was observed upon "pumping" protons away from the catalyst surface. The Faradaic efficiency (A) was lower than unity, indicating a sub-Faradaic effect. The highest value of rate enhancement ratio (p) was approximately 3.2, at T = 823 K. The proton transport number (PTN) varied between 0.45 and 1.0. An up to 99% of the produced H2 was electrochemically separated from the reaction mixture. (C) 2007 Elsevier B.V. All rights reserved.