A novel poly(phthalazinone ether ketone ketone) was prepared via the nucleophilic substitution polycondensation of bis-1,4-(4-chlorobenzoyl)benzene and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one. The synthesized polymer exhibited high glass-transition temperature, excellent thermooxidative properties, and fair rheological properties. The polymer was soluble in some polar solvents. Electronic friction and membrane properties are also discussed. The results indicate that the polymer falls in the class of high temperature resistance engineering plastics.