New kinetic data yielding a slower formation rate and larger absorption cross sections of Cl2O2 are incorporated into a photochemical model to reassess the role of chlorine chemistry in accounting for the ozone reductions derived from TOMS observations in different regions of the Antarctic polar vortex during 1987. The model is further constrained by existing measurements from the Airborne Antarctic Ozone Experiment (AAOE) and the National Ozone Expedition (NOZE) II. Calculated concentrations of ClO based on the new kinetic data increase by almost a factor of two between the collar and core regions of the vortex during the second half of September. As a result of the higher concentrations of ClO, the calculated ozone reductions in the vortex core appear to be still consistent with the TOMS observations in spite of the slower rate for the self-reaction of ClO. The agreement in the collar region is poorer. However, uncertainties in mixing, possible spatial inhomogeneities in both ClO and O3, the lack of more extensive data, and the uncertainties in the rate data and observations preclude determination of whether additional processes are required to account for the observed ozone removal in the collar region. ¿ American Geophysical Union 1990