Diffusion of water into Zr-containing silica fiberglass materials was studied at room temperature by infrared spectroscopy. Several types of experiments were performed: (a) rehydration with H2O of fiberglass materials previously calcined in air at 450 degrees C and under vacuum at 180 degrees C; (b) isotopic experiments for uncalcined fiberglass materials using D2O with and without the presence of sodium. Water diffusion coefficients were determined in each case. It was suggested that the transfer of the protons and water molecules occurred by different mechanisms: the protons diffused through the hydroxyl groups via the relay mechanism like in liquid water, whereas water diffused more slowly in the form of molecular water.