A poly(amic acid) derived from pyromellitic dianhydride and oxydianiline was imidized under different conditions. The sample imidized in solution (PI-1) showed the X-ray diffraction pattern of a crystalline material, whereas that of the sample imidized in the solid state was essentially amorphous. Both samples were further characterized by C-13-NMR spectroscopy, IR spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The orders of polyimide in both the crystalline and amorphous states are discussed. (C) 2004 Wiley Periodicals, Inc.