A great number of studies of polyelectrolyte complexes have been carried out by various investigators; most of them concentrated on the reaction between oppositely charged polyelectrolytes [1-3]. The structure and properties of the resultant complexes have been investigated to a lesser extent, and the understanding of this new class of polymer materials is still insufficient. Thus, we have been investigating the sorption of water vapor by the complexes and the morphological changes caused by this sorption [4,5].