The synthesis of N-phenyl phthalazinium salts by condensation of a 1,2-diaroylbenzene with phenylhydrazine is described. This reaction was utilized to prepare novel poly(aryl ether phthalazinium) ionomers by the direct condensation of poly(aryl ether ketone)s with phenylhydrazine. The preparation of poly(aryl ether phthalazinium) ionomers by methylation of poly(aryl ether phthalazine)s is also described. Most of the ionomers are amorphous, thermally stable, and soluble in organic solvents. They can be cast into flexible and strong films. The glass transition temperature of the ionomers ranges from 297 to 363 degrees C, an increase of 12 to 100 degrees C over the corresponding neutral polymers.