A spin cast film of poly(butylene terephthalate) (PBT) was analyzed by XPS using monochromatic AlKαexcitation. The measured atomic composition closely matched the expected stoichiometry of the polymer. Peak positions of the individual chemically shifted C 1sand O 1scomponents are reported. The results are in general agreement with other reported spectra of PBT polymers: experimental, C 74.8% and O 25.2%; theoretical, C 75% and O 25%.