alpha-Pinene enantiomers were sorbed in Nafion (R) membranes. The membranes included a commercial extruded Nafion (R) 115 membrane as well as membranes prepared by casting a Nafion (R) solution, evaporating the solvent, and a thermal treatment at different temperatures. The microstructure of membranes was studied by small-angle and wide-angle X-ray scattering, and magic-angle spinning nuclear magnetic resonance spectroscopy. The change of membrane weight during the sorption process was determined with a sorption microbalance. Noticeable differences concerning the sorption behavior of the various membranes could be stated. The sorption of (+)-alpha-pinene and (-)-alpha-pinene in an extruded Nafion (R) membrane turned out to be rather low.