This study aims to investigate the one-component permeation of carbon dioxide through two commercial perfluoroelastomers, Kalrez 6375 and Kalrez 7090, in long-duration tests (more than 30 days). The permeation rate in the cells filled with supercritical CO2 (SC-CO2) at the initial pressure of about p(in) = 41 MPa has been analyzed by measuring the pressure decrease over time at the constant temperature of about 334K. These measurements have revealed two distinct regimes of permeation which are separated by a local maximum at p similar to 12.5 MPa. In the lower pressure regime, the molar flux of the permeant linearly slows down with the pressure decrease. The high-pressure regime is characterized by a pressure independent molar flux of SC-CO2 through the elastomer. Considering the solution-diffusion model of permeation, we have developed a theoretical model describing the mass transport of CO2 through the elastomer at three different time scales. Its comparison with experimental observations provides insight into the fundamental aspects determining the membrane transport properties (diffusion, sorption, permeability). Application of the results for the plane sheet model to the realistic geometry of the sealing rings is discussed. (C) 2017 Elsevier B.V. All rights reserved.