The structural, energetic, electronic, vibrational, and magnetic properties of iron–benzene clusters, Fen–C6H6, n⩽7, were calculated using an all-electron density functional theory, DFT, with the generalized gradient approximation and the 6−311++G(2d,2p) basis set. A proposal regarding the mechanism of the adsorption of benzene on iron clusters related to the charge transfer model is described. A direct relation between the calculated electron affinity, EA, of the Fen–C6H6 clusters and their reactivity were also determined.