In a Proton Exchanging Membrane Fuel Cell (PEMFC), the membrane is at the heart of the assembly and is the place where electrochemical reactions happen. As water mobility governs these reactions, the Nafion polymer has been studied by NMR techniques (imaging, self diffusion…), but mostly outside a fuel cell. However, in an operating fuel cell, the membrane is exposed to multiple mechanicals constraints (hydration, swelling…). Therefore, we wanted to study the effect of such conditions on the water transport in the polymer. Three boundary conditions were investigated using different NMR techniques: -Stretching: Self diffusion experiments were performed on membranes under traction. Using a specially designed traction apparatus, we were able to measure diffusion anisotropy and to compare the results with experiments on membranes stretched outside the spectrometer. We demonstrated that this anisotropy is much higher in the case of in-situ traction in comparison with membranes stretched at high temperature before the experiment. We also developed a simple deformation model of the membrane in order to analyze the experimental results. -Compression: We used a home-made pressure chamber compatible with NMR experiments which allows us to apply on the membrane a pressure up to 140 bars. We then performed chemical shift, self diffusion and Single Point Imaging (SPI) experiments to see the effect of this pressure on the water transport. First results show that this pressure induces a decrease in water content and a slight reduction off the diffusion coefficient. Unlike stretching experiments, we were not able to observe any diffusion anisotropy. -Hydration and drying: We inserted the membrane inside a hydration cell inside the magnet. This device allows us to control the air humidity with the possibility to have different conditions on each side of the sample. We then performed SPI experiments across the membrane plane during hydration or drying phases. This allows us to visualize area in the membrane center with lower hydration and to extract drying and hydration kinetics constants from these experiments.