The number of bound water molecules restricted by mono-, di-, and trivalent cations in polyelectrolytes, such as polystyrene sulphonate, carboxymethylcellulose and alginic acid, was calculated using DSC. The number of bound water molecules decreases with increasing ionic radius in the series of mono- and divalent cations when polyelectrolytes form the liquid crystalline state. However, when polyelectrolytes form rigid junction zones in the presence of cations, the number of bound water molecules is maintained at a constant value regardless of ionic radius. The results indicate that the higher order structure of polyelectrolytes strongly influences the number of water molecules tightly bound by cations.