The anisotropic swelling of Nafion 112 foil in methanol-water-in organic salt was examined by the optical method. Our results show that even small addition of inorganic salt into methanol-water mixture affects kinetics as well as the swelling equilibrium. The effect of inorganic salts LiCl, NaCl, KCl, CsCl, CaCl2, CdCl2, K2CO3, KNO3, NH4Cl, and AgNO3 was studied. Swelling kinetics of Nafion in ternary mixtures including salt show maximum suggesting that in the beginning stage of swelling the diffusion of methanol is faster than ion transport. The experimental data, presented in this work, allow us to assume that swelling of Nafion decreases with increasing ionic radius of cation. (c) 2008 Elsevier B.V. All rights reserved.