Previously reported work by others indicates that dicopper trihydroxide nitrate, Cu2NO3(OH)3, forms on copper and copper alloys subjected to irradiated moist air near room temperature. We have performed experiments over a range of temperature and humidity, and have found that this species is formed at temperatures up to at least 150° C if low to intermediate relative humidities are present. At 150°C and 100% relative humidity, only Cu2O and CuO were observed. The relative general corrosion rates of the copper materials tested in 1-month experiments at dose rates of 0.7 and 2.0 kGy/h were Cu > 70/30 Cu-Ni > Al-bronze. High-nickel alloy 825 showed no observable corrosion.