Spray solutions would be used for pressure reduction and fission product absorption in the event of a serious accident in an aqueous power reactor. These sprays are normally alkaline borate solutions either with or without sodium thiosulfate added. The purpose of this investigation was to determine the corrosion resistance of materials normally present in reactors and associated containment systems in representative spray solutions. Our results showed that, as a class, aluminum alloys were very severely damaged by these solutions. A notable exception was the 5052 alloy which corroded much less at higher temperatures, but at about the same rate as the other aluminum alloys at the lower temperatures. Iron, nickel, copper, and zirconium-base alloys as well as structural concrete had adequate resistance to these solutions under all conditions tested. Pure copper was only lightly attacked by the alkaline borate solution, but with thiosulfate present the corrosion of copper was greatly increased.