An experimental method based on a gravimetric permeation cell was designed and successfully used in measuring the diffusivities, permeabilities, and the breakthrough times of several rubber-solvent systems. The experimental results for four organic solvents : benzene, o-xylene, ethylbenzene, and chloroform in silicone, natural, and bromobutyl rubbers, respectively, are reported along with a description of the experimental method. The relations between the diffusivities measured by a permeation method and a sorption uptake method are discussed. This permeation cell provides a simple and reliable mean to determine the diffusional transport properties of a polymer-solvent system.