Polyimide polyaniline nanocomposites were obtained by mixing poly{[4,4'-bis(4 ''-N-phenoxy)diphenylsulfone] imide-1,3-bis(3,4-dicarboxyphenoxy)benzene} (PI) and polyaniline (PANT) solutions in N-methylpyrrolidone. These solutions were used for the preparation of homogeneous and composite membranes. Uniform distribution of PANT particles in the membranes, resulted from interactions between macromolecules, was confirmed by transmission electron microscopy. Membranes based on PI and PI-PANI were tested in pervaporation of binary organic mixtures: methanol/toluene and methanol /cyclohexane and showed a remarkable selectivity with respect to methanol. In both pervaporation processes, selectivity was improved in PANT-containing membranes. Interactions between membrane polymers and liquid penetrants (methanol, toluene, and cyclohexane) were studied by measurements of surface tension, sorption, and pervaporation parameters. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2175-2182, 2010