The interactions of one and two benzene molecules with the superparamagnetic Fe-6 cluster were studied by means of gradient-corrected density functional theory. The ground state, GS, of bare Fe-6 presents a distorted octahedral structure with 2S = 20; S is the total spin. For the calculated 2S = 16 GS of the neutral Fe-6-C6H6 complex, as well as in the positive and negative ions both with 2S = 15, the benzene unit is adsorbed on one axial Fe-a atom. The 2S = 14 GS for Fe-6-(C6H6)(2) resembles a sandwich structure, with the metal Fe-6 cluster separating the benzene rings that are bonded symmetrically on the two axial sites of Fe6. The binding is accounted for by electrostatic interactions and by 3d-pi bonds, as revealed by the molecular orbitals. Though each C-Fe bond is weak, eta(6) coordinations were indicated by the topology of the electronic density. The 3d-pi bonding is reflected by the adiabatic ionization energies and electron affinities, which are smaller than those of bare Fe-6. The computed IR spectra show vibrational bands near those of bare benzene; some forbidden IR modes in benzene and in Fe-6 become IR active in Fe-6-(C6H6)(1,2). The results show a strong perturbation of the electronic structure of Fe-6. The decrease of its magnetic moment implies that the magnetic effects play an important role in the adsorption of benzene.