A joint effort has been undertaken, involving four laboratories and nine different analytical techniques, aiming at characterizing corrosion products on copper formed in mixed flowing gas test containing Cl~, H~S, and NO2. The results and considerations clearly show that the identification of different crystalline or noncrystalline phases in the corrosion products only can be performed by a combination of independently working analytical techniques. Cuprite, Cu20, is the dominating phase during initial exposure, whereas cuprite together with atacamite, Cu2CI(OH)3, are the most abundant phases after 10 days of exposure. In addition, the corrosion products contain minor amounts of sulfide, Cu2S, sulfate, most likely as posjnakite, Cu4SO4(OH)6 9 H20, and nitrate, most likely as gerhardite, Cu2NO3(OH)3. A nonstoichiometric cuprous oxide, Cu302, has also been detected by several techniques.

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