The polyaromatics are an important group of industrial polymers. For the highest performance applications the polyaryletherketones and polyarylethersulphones have proved very effective and have been successfully commercialised. Both polymer types, but mainly polyetheretherketone (Victrex PEEK), have been subjected to intense academic and industrial research in respect of their physical and chemical properties, thermal stability, irradiation resistance and their application in engineering and composite matrices. The synthesis of these polyaromatics has been widely studied but the nucleophilic polycondensation route is proving to be the only commercially viable one. Block copolymers have been synthesised, using transetherification to randomise polyaryletherketone‐co‐sulphone backbones as well as by utilising the reactive polymer end‐groups, and studied in considerable detail to establish structure–property relationships. Such end‐groups on arylethersulphone‐type polymers have also been used effectively in the development of tough, solvent‐resistant and easily processable thermoset–thermoplastic blends for use, in particular, as composite matrices. Pendant functionality has been studied as a route to improved properties and solvent resistance and is used commercially in the manufacture of polymers for membranes.