The anoxic corrosion of carbon steel liners inside failed copper nuclear waste containers is dependent on the composition of the groundwater to which it is exposed. The influence of carbonate/bicarbonate, sulfate, and chloride in solutions simulating concentrated groundwaters at pH 8.9 on the composition of the corrosion products formed on A 516 Gr 70 carbon steel has been investigated at room temperature. In situ Raman spectroscopic identification of the corrosion products formed during polarization at constant potential was conducted in a spectroelectrochemical cell. Siderite was established as the main product in sodium carbonate/bicarbonate solutions, and the observance of iron carbide indicates extensive steel dissolution in this environment. In mixed carbonate, sulfate, chloride solutions, compact deposits of carbonate-containing, and to a lesser degree, sulfate-containing green rusts were formed, along with small amounts of magnetite. In chloride-dominated solutions very thin, compact films, undetectable by Raman spectroscopy, were formed. Ex situ Raman analysis suggests this film may be magnetite. (c) 2006 The Electrochemical Society.