Metal dusting is a severe form of corrosive degradation of metals and alloys at high temperatures (350-950degreesC) in carbon-supersaturated gaseous environments. Fe, Ni, and Co, as well as alloys based on these metals are all susceptible. The corrosion manifests itself as a break-up of bulk metal to metal powder, hence, the term metal dusting. In the present study, metal dusting corrosion of pure cobalt is simulated in high carbon activity environments at temperatures between 350 and 950degreesC. The focus of this research is to understand reaction mechanisms by characterizing interfacial processes at the nanometer level. Cobalt corrodes by a combination of carbon diffusion and precipitation in the bulk metal and atom migration through surface carbon deposits. The nature of the carbon deposit is important in the overall corrosion process. (C) 2003 The Electrochemical Society.