In this work polysulfonamide membranes are presented that are prepared by the interfacial polymerization of polyethylenimine (PEI) and benzene-1,3-disulfonyl chloride (BDSC) on porous polyvinylidenefluorid support membrane. The thin film composite (TFC) polysulfonamide membranes show superior acid stability as compared to conventional polysulfonamide membranes that are derived from monomeric amine and benzene-1,3-disulfonyl chloride. The polysulfonamide membranes show exceptionally strong resistance towards nucleophilic attack induced by extreme acidic conditions. This is verified by the dyes rejection performance in 20%(w/v) H2SO4 and 2.5%(w/v) HNO3 aqueous solution at 70 +/- 5 degrees C for 24 h. PEI-PSA and PEI/PIP-PSA membranes were considerably stable in two acids. In contrast, the durability of PEI/MPD-PSA was lower than the other two. The changes in CV and MO dye rejection were -3.15% and -2.19%, and -1.11%, -5.6% for PEI-PSA and PEI/PIP-PSA, respectively after H2SO4 soaking while they were -20% and -15.9% for PEI/MPD-PSA. Moreover, the changes in CV and MO dye rejection were -15.7% and -14.3%, and -7.8%, -5.7 % for PEI-PSA and PEI/PIP-PSA, respectively after HNO3 soaking while they were -17.7% and -10.2% for PEI/MPD-PSA. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.