This thesis proposes a modeling approach of the chemical degradation by radcals attack of the mem-brane in polymer electrolyte membrane fuel cells, as well as its impact on the electrochemical per-formance degradation. The work considers a perfluorosulfonated acid type membrane. Its structure is strongly influenced by humidification, which also impacts the transport properties of mass and charge within the membrane. In order to study the degradation of the membrane, we first established a multi-species transport model for protons, water, and dissolved gases, radicals and ions. We then included detailed chemical reaction mechanisms of hydrogen peroxide formation, hydrogen peroxide decompo-sition, and radical attack of the membrane. Finally, a feedback between degradation, structure, and performance was established. Parameters were identified and the model was validated using literature experimental data both under performance and degradation aspects. The model was then exploited under different conditions, from pure laboratory conditions (constant current kept over a long time) to working conditions which are more representative of the use of a PEMFC for stationary applications (performance cycles).
