A difference in the UV photodissociation dynamics of chlorine and tricholorofluorocarbon has been observed when those molecules were adsorbed on water ice surfaces. This difference is mostly attributable to the difference in the interaction of the adsorbed molecule with surface water molecules of ice. In the photodissociation Of Cl-2 at 300-414 nm, the branching ratios of the formation of Cl-.(P-2(1/2)) with respect to Cl(P-2(3/2)) are different from those reported in the gas-phase photodissociation. However, in the photodissociation of CFCl3 at 193 nm, the ratio is in good agreement with that reported in the gas-phase photodissociation. The kinetic energy distributions of the photofragment chlorine atoms reflect the interaction between the adsorbates and the surface water molecules.