A flow system incorporating Pirani gauges was used to measure the sorption of hydrogen activated by an rf discharge by Vycor glass. The sorption was dependent on the pressure and the discharge intensity. A rapid, initial adsorption was followed by a slow sorption which obeyed at1/2law but then decelerated. The kinetics of the thermal release of hydrogen from the Vycor also followed at1/2law. The data suggest that a steady-state condition, dependent on the hydrogen-atom population in the gas phase, was established on the surface. Hydrogen diffused into the bulk, the rate being a function of the heating of the Vycor surface by hydrogen-atom recombination. Molecular hydrogen diffused to the surface when a sample was heated.