Within this study we present experimental data on the performance of a single cell PBI-based high-temperature fuel cell operated with synthetic reformate and oxygen enriched air. A test studying different concentrations of oxygen in cathode air revealed that 30% V/V oxygen concentration allowed kinetics improvement and could prevent corrosion occurring with higher oxygen concentrations. A long term accelerated stress test, consisting of load cycling between open circuit voltage and a load of 0.3 A/cm(2) was implemented to investigate fuel cell degradation. A degradation rate of -81 mu V/h has been determined under such harsh operating conditions. Electrochemical characterization has been performed to clarify the causes of degradation. Loss of the electrochemically active surface area seems to be the major contribution caused by the accelerated stress test. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.