Polyesters of para-oxybenzoyl are infusible and very resistant to acids and solvents, thus limiting the means by which such polymers can be fabricated. Such a polyester is made more amorphous, thus improving compression moldability, by subjecting it to a high temperature treatment, followed by a rapid quench. The resulting polymer has reduced crystalline orientation, as evidenced by X-ray diffraction patterns, and molded articles thereof have improved flexural strength, without adversely affecting the modulus. The thermal treatment is carried out on the polymer by heating at a temperature of at least 300.degree.C, and up to just below the decomposition temperature of the polymer, followed by quenching of the hot polymer.