Nanosecond laser photolysis studies of chloropyridinato- and chloroaquachromium(III) tetraphenylporphyrin, (ClCrTPP)-T-III(Py) and (ClCrTPP)-T-III(H2O), dissolved in polystyrene films have been carried out in the temperature range 77-300 K. The transient observed for (ClCrTPP)-T-III(Py) after laser pulsing is solely the excited states (the tripquartet, T-4(1), and tripsextet, T-6(1), states). The emission from the tripquartet state, T-4(1), is detected upon laser excitation of (ClCrTPP)-T-III(Py). No photodissociation of axial pyridine is detected in the temperature range studied. The laser photolysis of (ClCrTPP)-T-III(H2O) in polystyrene films gives two transients; the excited states (T-4(1) and T-6(1)) Of (ClCrTPP)-T-III(H2O) and the five coordinate (ClCrTPP)-T-III yielded by the photodissociation of axial H2O from (ClCrTPP)-T-III(H2O). The yields of the excited states (T-4(1) and T-6(1)) for both (ClCrTPP)-T-III(Py) and (ClCrTPP)-T-III(H2O) were found to increase with a decrease in temperature. The lifetimes and the relative yields of the excited states and the relative yields of the photodissociation of the axial ligands were measured in the temperature range 77-300 K, These results lead to the conclusions that (1) the energy gaps between the T-4(1) and T-6(1) states are 1.5 and 1.1 kcal mol(-1) for (ClCrTPP)-T-III(Py) and (ClCrTPP)-T-III(H2O), respectively, (2) the full photodissociation of axial H2O from (ClCrTPP)-T-III(H2O) occurs from the singquartet state, S-4(1), and (3) the photodissociation of the axial ligand Is the major pathway for excitation energy dissipation at the S-4(1) state of six-coordinate chromium(lII) porphyrin.