Compositions and methods for a melt processable semicrystalline poly(aryl ether ketone) incorporating phthalazinone and 4,4′-biphenol as comonomer units are described herein. The polymers are resistant to and insoluble in common organic solvents and liquids as well as in aggressive organic solvents such as chloroform and chlorinated liquids. The polymers are melt processable via techniques such as extrusion, injection molding, and compression molding. The semicrystalline poly(aryl ether ketone) containing phthalazinone comonomer units have properties which make them suitable for manufacturing high temperature resistant molded systems and other articles.