The main objective of the planned project DECODE is to increase the life-time of fuel cells for automotive applications. It is well-known that liquid water plays a crucial role in the degradation processes of fuel cells. However, this specific degradation influence is not addressed sufficiently in the present research and development efforts. Therefore, DECODE aims at identifying characteristic behavior regarding degradation and malfunctions with special emphasis on liquid water interactions. The work will quantitatively elucidate fundamental degradation mechanisms with PEFC under steady-state, cycling and start-up/shut-down conditions. The elucidated mechanisms will be used to improve PEFC durability. The project plan is spitted into three phases: In the first short phase, - the specification and definition phase -, materials, components as well as testing and opera¬ting conditions will be specified. In the second phase, - the analysis phase - the individual degradation processes of the components and their interactions will be investigated. This includes the fundamental investigation of membrane and electrodes in work package 3, the analysis of porous media in work package 4 and the investigation of degradation of bipolar plates in work package 5. The investigations in these three work packages involve novel methodology, sophisticated characterization of components, and modeling of water transport and water interactions with components. In the third phase the knowledge of the degradation processes and mechanisms will be use to generate technological progress. It includes development of novel fuel cell operating strategies to mitigate degradation phenomena and to improve components and single cell design (also by moderate modification of materials).