The effect of high pressure on the electrical conductivity and proton, deuteron and O-17 NMR in acid form NAFION-117 conditioned at various levels of relative humidity has been determined. NMR measurements of T-1 were carried out as a function of pressure up to 0.25 GPa. The complex impedance studies were made along the plane of the film at frequencies from 10 to 10(8) Hz at room temperature and pressures up to 0.3 GPa. The electrical conductivity and proton and deuteron NMR measurements show that the activation volume for materials containing greater than about three water molecules per sulfonate is 2-3 cm(3) mol(-1) and larger values are found as the amount of water decreases. The implications of these results are discussed. The O-17 NMR results are unexplained at the present time.