A process for producing aromatic polyether ketones and polythioether ketones, which comprises reacting aromatic ethers or thioethers represented by the general formula: ##STR1## where each of R1 to R12 is a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group, n is an integer of 0 to 5, and X is an oxygen atom or a sulfur atom, with phosgene in aprotic solvent having a dielectric