The atmospheric rate of photolysis of the ozone-water weakly bound complex, O3⋅H2O, is evaluated. On the basis of this information, we discuss the potential role of this chemistry in the production of OH in the troposphere. While there are uncertainties inherent in the experimental database available for O3⋅H2O, the calculations show that photolysis of this complex is a potentially significant tropospheric OH source. ¿ American Geophysical Union 1995