Differential heat effects and rates of H2O sorption and desorption are investigated in the polyacrylamide (PAA)-water system at 0n(eq) they are equal to Q(L). It is concluded that sorption of water by dry PAA leads to linearization of PAA molecules, to the space between the amido groups of each PAA molecule being filled with water, and to neighboring order at which each PAA molecule is surrounded (at the section normal to the main carbon chain) by six nearest ones. At equilibrium, the PAA molecules are separated from each other by a water layer of three-molecule thickness.