Water diffusion into the polymer electrolytes (Pb, Zn)(CF3SO3)(2)(PEO)(n) leads to a dramatic increase of the ionic conductivity. Magnetic resonance imaging, MRI, has been used to study this water diffusion by one-dimensional mapping of properties such as spin density and relaxation times. The line widths are of a comparable magnitude for the polymer material and the absorbed water, which has been used to perform parallel studies of both components in the MRI experiments. The water absorption in the materials studied can be classified as Fickian diffusion. The effect of water ingress on crystallinity in semicrystalline samples with two-dimensional MRI has also been recorded. Water is absorbed mainly by the amorphous regions, although the diffusion of water through the sample is accompanied by a rapid destruction of the crystalline regions.