Abstract: The corrosion products of boiler tubes, economizer and superheater were studied by Mossbauer spectroscopy. It was found that the a-Fe₂O₃ content in the corrosion products increased, but the Fe₃O₄ content decreased, with increase of corrosion time. The corrosion process of boiler tubes should be. formation of Fe₃O₄ first, and further oxidation of Fe₃O₄ to a-Fe₂O₃ . It was also found that I_B/I_A was<<2 in Fe₃O₄. This phenomenon was probably caused by incorporating some other ions into Fe₃O₄. The results were complemented by X-ray diffraction, infrared spectra, chemical analysis and electron probe analysis.