High molecular weight copoly(ether ketone)s (PEK) based on 4-(4-hydroxyphenyl)-1- phthalazinone (DHPZ)/4,4-thiobisphenol (TBP)/4,4-diflourodiphenylketone (DFK) were prepared by nucleophilic substitution polycondensation. The copolymers were characterized by FT-IR and 1H-NMR. Thermal properties and solubility of copolymers were studied. High molecular weight copolyether ether (PEK) based on 4- (4-hydroxyphenyl) -1-phthalazinone (DHPZ) / 4,4-thiobisphenol (TBP) / 4,4-diflourodiphenylketone (DFK) were prepared by nucleophilic The polyacrylates of these copolymers were characterized by FT-IR and 1H-NMR. Thermal properties and solubility of copolymers were studied.