The transport behavior of aromatic hydrocarbons in crosslinked nitrile rubber (NBR) membranes has been studied in the temperature interval of 28°–70°C. NBR was cured by different vulcanizing techniques, viz., efficient, conventional, peroxide, and mixed. The peroxide system showed the lowest solvent uptake; and the conventional system, the highest. The effect of penetrant size on the sorp-tion behavior of NBR was investigated. In all the systems the mechanism of diffusion showed an anomalous behavior. From the sorption data, the interaction parameter, molecular weight between crosslinks, Arrhenius activation energies, and thermodynamic quantities such as enthalpy and entropy changes for sorption processes were calculated. The first-order kinetic equation was used to study the sorption kinetics. Finally, the experimental sorption data were compared with theoretical predictions.