Abstract: aromatic polymers having phenylene groups linked by oxygen atoms, ketone groups and sulphone groups, that is etherketone/sulphone copolymers, containing 40 to 90 and preferably 50 to 80, mole % of the repeat units ##STR1## and correspondingly 10 to 60, particularly 20 to 50, mole % of repeat units ##STR2## where Q and Q' are --SO.sub.2 -- or --CO--, the number of --SO.sub.2 -- groups being 3 to 25% of the total number of --SO.sub.2 -- and --CO-- groups are disclosed. Such copolymers are made more cheaply than the similar copolymers of U.K. Pat. No. 1,414,422 yet exhibit improved properties of a somewhat reduced melting point, owning to the incorporation of sulphone linkages in the polymer chain, thus providing greater latitude over processing temperatures. Preferably from 10 to 20% of the total sulphone and ketone linkages in the copolymers are sulphone linkages. The disclosed copolymers are particularly suitable for wire insulation where the polymer has to retain its properties at high service temperatures.