The SrBi2Ta2O9 (SBT) films studied for this report were prepared by metalorganic decomposition. The SBT thin film, which belongs to a Bi-layered perovskite structure where double Ta–O octahedron layers are sandwiched between (Bi2O2)2+ layers, was analyzed to characterize chemical states using x-ray photoelectron spectroscopy during depth-profiling analysis. When sputter etching was performed on the SBT film by Ar+ ion bombardment, the chemical states of constituents in the SBT film were changed as a function of the applied Ar+ ion-beam energy. Among the constituents of the SBT film, the Sr 3d peak was changed slightly by the change of Ar+ ion-beam energies. On the other hand, the changes of Ta 4f and Bi 4f peaks obviously depended on the applied Ar+ ion-beam energies. In particular, the Bi 4f peak changed dramatically from Bi–O states to Bi metallic states by the lower Ar+ ion-beam energies than in the cases of Sr and Ta. This change of chemical states of the SBT film resulted from the preferential sputtering of oxygen atoms. Following our present study, preferential sputtering of oxygen atoms was found to depend on the thermal stability and mass difference between oxygen and each constituent within the SBT films. © 2001 American Vacuum- - Society.