Crosslinked poly(ether ether ketone) membranes were prepared from lab-synthesized polymers via the phase inversion process. Commercially available diphenolic acid and difluorobenzophenone were selected as monomers introducing a functional group, carboxylic acid, into the resulting polymer that could later be used to crosslink the membranes with diamines. This reaction was realized already during the stage of membrane formation since the diamines were added to the coagulation bath. The reaction was monitored by FTIR and stability tests. The diamines were varied in their concentration and structure to find the optimal crosslinking conditions. The thus prepared solvent resistant nanofiltration membranes were stable in many solvents such as acetone and showed high rejection of rose Bengal in isopropanol and acetone. (c) 2013 Elsevier B.V. All rights reserved