The dielectric properties of polystyrenesulfonic acid membranes in their hydrogen form have been studied over the frequency range of 102–105 Hz, with water content and temperature as parameters. Dielectric dispersion is observed for slightly wet sulfonate membranes and is considered to be water‐induced. Two distinct membrane hydration stages have been noted at low water contents. Dielectric dispersion processes of the wet ionic membrane in its sodium and potassium forms are also discussed.