Polysulfone/MMT nanocomposite membranes were prepared by a congruence of the wet-phase inversion and the solution dispersion techniques. Different clay contents and two kinds of polysulfone were used in order to investigate the changes in the nanocomposite structure as well as in the thermal and mechanical properties. The increase in the basal spacing with the clay content increase was revealed by SAXRD. TEM images depicted the presence of hybrid morphology and SEM images showed that the clay particles were trapped inside the cross-section pores. By increasing the clay content and polysulfone molar mass, the onset temperature of decomposition was increased and the mass loss was decreased. From DTA studies, it was observed that PSf P-1700 low clay content membranes had higher values of enthalpies and the enthalpy values of PSf P-3500 membranes did not present a regular behavior. Also in the tensile tests, the increase of the clay content up to 4.0 mass% promoted the increase of elongation at break and tensile strength. (C) 2013 Elsevier B.V. All rights reserved.