In earlier publications it has been reported that plasmapolymerized organosilicon films may contain up to 6.8 wt% water. A distinction has been made between “weakly” and “strongly” bound water in the polymer matrix, the strongly bound water being incorporated into the film in the form of network aggregates connected with the glass by means of hydrogen bonds. The observation in those materials of a phase transition is due to the changed inner structure of the aggregates in question. The goal of this study is the determination of the effect of absorbed water on the dielectric properties of plasma-polymerized organosilicon films. It is shown that the weakly bound water activates a relaxation process whose frequency at room temperature is above 0.5 MHz. In contrast, the strongly bound water reveals its presence by two relaxation processes of very low frequency, with activation energies of 0.65 eV and 0.87 eV. It was found that the absorbed molecules of strongly bound water may also inhibit the rotation of certain matrix dipoles.