The affinity of polar extractants (propylene carbonate, dimethylsulfoxide, dimethylformamide, triethylene glycol and dimethylacetamide) and benzene, toluene, p-xylene and m-xylene (so-called BTX fraction) for PIM-1 material was evaluated. The mass-transfer coefficients of selected solvents were determined in organic solvent nanofiltration process. All solvents showed a good affinity toward PIM-1 polymer; while the large values of sorption and PIM-1 swelling degree were in the case of benzene (1.63 g/g, 192%), toluene (1.72 g/g, 186%) and xylenes (1.61-1.76 g/g, 147-170%); while these values for selected polar solvents were in the range of 1.09-1.48 g/g and 83-108%, respectively. The values of sorption and swelling degree were successfully correlated with Hansen's solubility parameters. Values of permeability coefficients of nonpolar solvents through PIM-1 membranes were 1.5-5.5 times higher than those for polar solvents. With increasing affinity of the solvent toward polymer, the values of the permeability coefficients also increased.