Predicted infrared vibrational spectra of low-energy isomers of rhodium cluster oxides, Rh6Om+ (m = 1-4), are presented, based on structures calculated using density functional theory. The oxygen stretching frequencies are found to be characteristic of the oxygen binding mode. These simulated spectra provide a guide to future experimental measurements of the infrared multi-photon dissociation spectra, enabling assignment of the binding sites of oxygen atoms on the cluster. In favourable cases these calculations suggest that a determination of the underlying metal framework structure is possible. (C) 2008 Elsevier B.V. All rights reserved.