The photoexcitation of Rh-I(CO)(2)/Al2O3 has been studied by infrared and ultraviolet absorption spectroscopy. A photodissociation energy threshold between 2.8 and 2.9 eV, for the Rh-I-CO bond of the Rh-I(CO)(2) species, has been determined by monitoring the depletion of the CO moiety, leading to the production of a highly active surface site. A Rh-I-CO photodissociation cross section of 3.6 x 10(-20) cm(2) photon(-1) and a quantum efficiency of 0.01 [Rh-I-CO dissociation] photon(-1) has been estimated for the initial stages of Rh-I(CO)(2) photodepletion. Three absorption bands, observed at 3.3, 3.9, and 4.6 eV in the ultraviolet absorption spectra, are assigned to electronic transitions from filled Rh d-character molecular orbitals to d-character and/or ligand-based antibonding orbitals. Photodissociation of the Rh-I-CO bond occurs from the direct excitation of Rh-I-(CO)(2) species. During later stages of photolysis, the role of depletion of Rh-I (CO)(2) decreases dramatically and this effect may be due to the slow diffusion of CO through the pores of the Al2O3 support.