The photolytic cage effect was studied over a wide d. range of several bath gases in the laser flash photolysis of I2 at 694.3 nm. Particular attention was paid to measurements in the simple solvents Xe and Kr, which were compared with mol. dynamics calcns. Measurements in polyat. gases and liqs. were made, as well as the variation of the cage effect with temp. and applied magnetic field. While measuring the cage effect under a wide variety of conditions, the second order rate consts. for I atom combination were also obtained.