The effect of temperature on the heavy isotope ratios of the products (CO and O-2) of photolysis of CO2 by similar to 185 nm photons was studied. The isotope ratios O-18/O-16 and O-17/O-16 in O-2 and CO and C-13/C-12 in CO increase with temperature by similar to 1% per K. The increase in O-17/O-16 in O-2 is related linearly to the increase in O-18/O-16 with a slope 0.8 contrary to the mass dependent value of 0.5. Variations in factors related to the transition dipole moment and Boltzmann distribution of the vibrational state populations are probably responsible for the observed change. Temperature dependence of the gas production rate agrees with the reported cross-section variations. (c) 2009 Elsevier B.V. All rights reserved.