Laser-ablated Rh+, Rh, and electrons react with CO on condensation in excess neon at 4 if to form RhCO+, RhCO, RhCO-, and Rh(CO)(2)(+), Rh(CO)(2), Rh(CO)(2)(-), and higher carbonyls: These rhodium carbonyls are identified by isotopic substitution ((CO)-C-13, (CO)-O-18, and mixtures), electron trapping with added CCl4, and comparison with DFT calculations of isotopic frequencies. This is the first spectroscopy of isolated rhodium carbonyl cations and anions. The isolated monocarbonyl species provide a scale to estimate local charge on Rh(CO) sites in catalyst systems.