Аннотация:The olefin separation from their mixture with paraffins by facilitated transport membranesis a very important process for the further macromolecular compounds production. Membranesloaded with silver ions, which are responsible for the facilitated olefin transport, are instable withtime due to their reduction, while those containing protons catalyze the polymerization of olefins. Inthis work, membranes based on polyethylene with grafted sulfonated polystyrene in various ionicforms (H+, Li+, Na+) were used for the first time for the separation of the ethylene/ethane mixture.The influence of sulfonation time, relative humidity, and various ionic forms on ethylene separationwas studied. The SEM study shows a non-uniform sulfur distribution over the membrane thicknessfor membranes sulfonated for different reaction times. With increasing sulfonation time and relativehumidity the ethylene permeability and the factor of its separation with ethane increase. Separationfactors for membranes in the Li+-form are shown to be as high as for membranes in the H+-form. Apossible mechanism for the facilitated ethylene transport is discussed.