Characterization of the rust formed during long-term atmosphere exposure at Beijing station on carbon steels pre-corroded by different gaseous pollutants was performed by means of Fourier transform infrared spectroscopy and X-ray diffraction. Goethite (alpha-FeOOH), Lepidocrocite (gamma-FeOOH) and Feroxyhite delta-FeOOH are identified in the rust formed on all of the samples independent of the different pre-corrosion conditions and the different carbon steels. The results also show that: the rust constituent of the same kind of carbon steel pre-corroded by different pollutants are the same; the rust of carbon steels exposed for one year is some different to that exposed for two years; the phase constituents of the inner rust at the upper surface are the same as that at the downward surface, but those of the outer rust are different. It is concluded that the phase constituents of the rust of the same kind carbon steel after one year are the same under the different pre-corrosion conditions. (C) 2003 Kluwer Academic Publishers.