Аннотация:The article presents data on the synthesis and properties of amorphous random cardo copoly(arylene ether ketones), obtained by polycondensation by the mechanism of the nucleophilic substitution reaction of activated halogen in aryl dihalide by the interaction of 4,4′-difluorobenzophenone with a mixture of dipotassium diphenolates of three bisphenols in N,N-dimethylacetamide. The synthesis of copolymers with a given molecular weight, characterized by great structural microheterogeneity has been carried out at a non-equimolar ratio of monomers (excess of bisphenols) and blocking of the end phenolic groups with a monofunctional reagent, 4-fluorobenzophenone. The structure of the synthesized copolymers has been confirmed by the data of 13C NMR, which correspond to the proposed structure of the co-PAEK. It is shown that the synthesized copolymers have good mechanical properties and the softening starting point in the range from 180 to 240°C.