The present density functional theory study provides insight into the effect of Fe promotion on the CO dissociation reaction on a stepped Rh surface. On the basis of a density of states analysis we demonstrate that Fe is able to promote the CO dissociation reaction by stabilizing the oxygen atom in the transition state. This effect critically depends on the location of the Fe substitution in the Rh(211) surface and the pathway of the CO dissociation reaction. This work explains the higher activity and selectivity encountered in experimental studies during CO hydrogenation on Rh nanoparticles. (C) 2015 Elsevier B.V. All rights reserved.