We report for the first time successful crosslinking of polyamide-imide (Torlon (R)) based membranes using di-isocyanates. The crosslinked membranes are resistant to N-methyl pyrrolidone (which is solvent of the non-crosslinked membranes) and have very good mechanical properties. In contrast to the state-of-the-art polyimide crosslinked membranes, the created covalent bond is expected to be thermally stable enabling applications at elevated temperatures. The transport characteristics (permeance and molecular weight cut off - MWCO) of the crosslinked membranes are changed in comparison to non-crosslinked ones. This suggests that the crosslinking process could be used to tailor these characteristics. (C) 2012 Elsevier B.V. All rights reserved.