The heterogeneous reactions of CF3OH with bulk liquid water and sulfuric acid solutions were studied in wetted-wall flow reactors with chemical ionization detection of CF3OH. Heterogeneous reaction probabilities (&ggr;) increases strongly with increasing activity of water (e.g., &ggr;=4¿10-4 on 60 wt% H2SO4 at 206 K and 8¿10-2 on 40 wt% at 211 K). The heterogeneous loss of CF3OH was also studied on submicron sulfuric acid aerosol in an atmospheric pressure laminar flow reactor. The aerosol reaction probabilities increase linearly with increasing particle radius (r<0.5 μm, 40 and 50 wt% sulfuric acid at 250 K), suggesting that CF3OH uptake is volume limited for stratospheric aerosol. These measurements indicate that CF3OH will have a lifetime of a few days in the troposphere due to its loss on cloud particles, but a much longer lifetime with respect to heterogeneous loss in the stratosphere. ¿ American Geophysical Union 1995