Nafion, a solid perfluorinated polymeric sulfonic acid, reacts readily with bases and can thus be converted to a tremendous number of individual modifications. A survey of spectral, mechanical, thermal, and pervaporation characteristics of Nafion modified with simple inorganic and organic bases and with the derivatives of amino acids is thus reported. The spectral characteristics, thermal stability, and T-g changed pronouncedly for Nafion modified with the stronger bases, such as ammonium or tris(hydroxymethyl)aminomethane, while minor changes were observed for Nafion modified with the derivatives of amino acids. Permeability and selectivity of Nafion observed for the pervaporation of methanol-dimethyl carbonate and methanol-methyl acetate mixtures were mainly influenced by the modification with amines bearing hydroxyl and, most pronouncedly, sulfo groups. Importantly, the pervaporation membrane from Nafion modified with taurine appeared similarly permeable and hygroscopic but more methanol-selective than that from pure Nafion.