Aromatic poly(ether ketone)s (PEKs) were modified with various amount of C36 dimer acid Pripol 1017 obtained from polymerization of unsaturated C18 fatty acids. To obtain modified PEKs, polycondensation was carried out using various dicarboxylic acids with diphenylether at 75 degrees C in phosphorus pentoxide/methanesulfonic acid as condensing agent and solvent. The reduced viscosities of polymers are relatively low, up to 0.13 dL/g. PEK with a structure (molar ratio of aliphatic to aromatic segment : 0.33) is soluble in organic polar solvents and can be cast from a tetrahydrofuran solution with cobalt naphthenate air dryer in order to obtain crosslinked film at room temperature. (C) 1997 John Wiley & Sons, Inc.