This letter challenges the concept that Fe-0/Me-0 bimetallic systems enhance contaminant reduction on Me-0 surfaces. It is shown on a pure thermodynamic perspective that any enhancement of contaminant reduction by Fe-0 in the presence of a second more electropositive elemental metal (Me-0) is the result of an indirect process resulting from iron corrosion. This demonstration validates the concept that aqueous contaminant removal in the presence of Fe-0 mostly occurs within an in situ generated oxide film on Fe-0. (C) 2008 Elsevier B.V. All rights reserved.