The effect of hydrogen partial pressure (1.3-5.8 kPa) and cell temperature (600-800 degrees C) on the kinetics and mechanism of the charge transfer electrode reaction taking place at the three phase boundary H-2-Fe-SCY (SCY = SrCe0.95Yb0.05O2.975), was thoroughly examined by performing electrode polarization measurements. A three electrode single chamber proton conducting solid electrolyte cell of the type Fe-SCY-Au, was used in order to conduct the electrode kinetic studies. The steady-state current-overpotential characteristics were analysed with the high field approximations of the Butler-Volmer equation, by taking into account the presence of limiting currents. Both, apparent exchange current density, I-o, and anodic/cathodic charge transfer coefficients (alpha(a)/alpha(c)), were calculated. Limiting currents, I-I, were observed in all reaction conditions. The apparent reaction order, q, was found in most cases, within experimental error, close to 0.5 suggesting a possible reaction model, where a competition exists between charge transfer and mass transport of hydrogen ad-atoms or protons along the electrode/solid electrolyte interface. (C) 2007 Elsevier B.V. All rights reserved.