The synthesis of a novel chloro monomer containing the 1,2-dibenzoylbenzene moiety was described. The chloro monomer was reacted with 4-(4-hydroxyphenyl)-1(2H)-phthalazinone compound in the presence of excess anhydrous potassium carbonate in an aprotic solvent (Sulfolane), and high molecular weight amorphous poly(aryl ether ketone ketone) was synthesized. The polymers with high glass transition temperature were soluble in solvents such as chloroform and nitrobenzene at room temperature and easily cast into flexible, colorless, and transparent films. The 5% weight loss of the polymers was >400 degreesC.