Tough crystalline thermoplastic aromatic polyetherketones containing the repeat units ##STR1## alone or in conjunction with other repeat units especially ##STR2## and having an inherent viscosity IV of at least 0.7, preferably at least 0.8. The polymers may be made by condensation of hydroquinone, 4,4'-difluorobenzophenone and an alkali metal carbonate or bicarbonate in the presence of an aromatic sulphone solvent, e.g. diphenylsulphone, at 150.degree.-400.degree. C. The polymers are very useful for wire coating.