High molecular weight semicrystalline poly(aryl ether ketone)s have been prepare from hydroquinone and 1,3-bis(4-chlorobenzoyl)benzene in diphenylsulfone and anhydrous potassium carbonate with or without toluene. The use of this solvent system, instead of a combination of dimethylacetamide, diphenylsulfone and toluene, results in the elimination of S(RN)1 (radical nucleophilic, unimolecular substitution) processes and the formation of high molecular weight polymer takes place entirely via S(N)AR (nucleophilic aromatic substitution) reactions.