Time-resolved infrared spectroscopy has been used to probe the nu(CO) bandwidths of the MLCT excited states of carbonyl-containing metal complexes, in both polar and nonpolar solvents. Considerably broader excited state bands observed in the polar solvents indicate that the broadening of the nu(CO) bands is a consequence of solvent-solute interactions. pi pi* excited states, with no charge-transfer character, exhibit no such broadening of the nu(CO) bands upon excitation.