Separation of beta- and gamma-picolines from water using elastomeric membranes has been studied. PDMS and EPDM membranes were found to afford separation with good selectivity and flux over the entire concentration range. Natural rubber and nitrile-butadiene rubber membranes caused only a shift in the binary distillation azeotropic composition. Data from sorption and permeation studies were used to calculate the heat of sorption and activation energy for diffusion as a function of the picoline concentration. The activation energy for diffusion was found to decrease with increasing picoline concentration in agreement with the theory of plasticization.