AbstractAqueous contaminant removal in the presence of metallic iron is often regarded as a reductive transformation mediated by the Fe0 surface. However, successful removal of theoretically nonreducible contaminants has been largely reported. This article presents a rebuttal of the concept of contaminant reductive transformation. It is argued through a careful examination of the evolution of the volume and adsorptive properties of iron and its corrosion products that contaminants are primarily adsorbed and coprecipitated with iron corrosion products. One may wonder how the Fe0 technology will develop with the new concept. © 2009 American Institute of Chemical Engineers Environ Prog, 2010