Flash and continuous photolysis studies of (mu-pdt)[Fe(CO)(3)](2) under excess CO were conducted in coordinating and noncoordinating solvents. The back-reaction of CO with the photoproduct showed second-order kinetics with k(CO) values of 1.0 x 10(8), 3.4 x 10(6), 1.2 x 10(6), and 0.90 M-1 s(-1) in hexanes, benzene, toluene, and THF, respectively. These data indicate a solvent-coordinated intermediate as one photoproduct, but other long-lived species were also apparent.