Hexafluorodianhydride-oxydianiline (HFDA-ODA) polyimide was characterized using x-ray photoelectron spectroscopy (XPS). Elemental composition and polymer stoichiometry as elucidated with XPS are reported. The HFDA-ODA polymer cured at 360 °C was fully imidized giving rise to a single nitrogen 1s peak at 400.8 eV. The carbon 1s data showed an unexpectedly large peak at 285.9 eV. This peak could not be justified only by C-N and C-O electrons, but required the carbon 1s electrons from the HFDA aromatic rings to be included. The small peak at 287.5 eV was assigned to the tertiary carbon Is electrons of the C(CF3)2group. The carbon 1s data interpretation is substantiated by molecular orbital calculations. © 1987, American Vacuum Society. All rights reserved.