Poly[oxy-(2,5-dibenzoyl-1,4-phenyleneoxy)-1,4-phenylenel] (3) was prepared by the aromatic nucleophilic substitution reaction of 2,5-difluoro-4-benzoylbenzophenone (2) with hydroquinone (1) in the presence of potassium carbonate in diphenylsulfone. The polycondensation was conducted at 150-320 degrees C for 4 h and produced polymer 3 at excellent yield levels. Polymer 3 was characterized by elemental analysis, i.r. spectroscopy, differential scanning calorimetry (d.s.c.) and wide angle X-ray measurement (WAXD). Polymer 3 showed two endothermic peaks on d.s.c. scans, which would be attributable to recrystallization effects; the lower-temperature endotherm represented only a portion of the melting endotherm of original crystals and the upper-temperature endotherm was the melting of crystals reorganized during a heating scan.