Two series of novel copoly(arylene ether ketone) were successfully synthesized from hydroquinone or bisphenol A, bis(4-fluorophenyl)ketone and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one with anhydrous potassium carbonate as the catalyst. The synthesized polymers exhibited high glass-transition temperatures together with excellent thermooxidative stability. The chain structure of these polymers was studied by means of C-13-nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD) techniques. The experimental results showed that these "as-made" copolyaryleneketones containing hydroquinone moieties exhibited a multiblock chain structure with long segments that mainly consisted mainly of hydroquinone and bis(4-fluorophenyl)ketone at the middle of the molecular chain. These long segments exhibited crystallites in the produced polymers. The synthesized copolyaryleneketone containing 90 mol % hydroquinone possessed a glass-transition temperature higher than that of commercial PEEK. The synthesized polymers also exhibited either fair processability or solubility. The glass-transition temperatures, solubility, and tensile strengths of the two series of copoly aryleneketones tended to increase with increasing phthalazinone moiety content.