In this contribution we demonstrate the potential of model studies for the understanding of electrocatalytic reactions in low-temperature polymer electrolyte fuel cells (PEFCs) operated by H-2-rich anode feed gas, in particular of the role of temperature effects and catalyst poisoning. Reviewing previous work from our laboratory and, for better comparison, focussing on carbon-supported Pt catalysts, the important role of using fuel cell relevant reaction and mass transport conditions will be outlined. The latter conditions include continuous reaction, elevated temperatures, realistic supported catalyst materials and controlled mass transport. The data show the importance of combining electrochemical techniques such as rotating disc electrode (RDE), wall-jet and flow cell measurements, and on-line differential electrochemical mass spectrometry (DEMS) under controlled mass transport conditions. (c) 2005 Elsevier B.V. All rights reserved.