The photochemistry of chlorine dioxide, OClO, in polycrystalline ice has been investigated at T=140-185 K using FTIR and UV-vis spectroscopy. Photolysis with ultraviolet light at 360 nm produced chloryl chloride, Cl-(OClO). The unique vibrational bands at 1210, 1040, 520 and 430 cm(-1), along with the characteristic UV absorptions at 300 and 235 nm, were used for definitive assignment of the photochemical product. The proposed mechanism for the formation of Cl-(OClO) involves photolysis of OClO to Cl + O-2 followed by migration of the Cl to a nonphotolyzed OClO. While clustering of the OClO may play a role in the formation of the product, experimental evidence indicates that the OClO prefers to exists as a monomer solvated by the water. These results have potential implications for stratospheric ozone loss : under the very dilute conditions that would exist on polar stratospheric ice particles, the photochemical conversion of OClO to Cl+O-2 would represent a new source of Cl atoms for ozone depletion.