The destruction of ozone on ice surfaces was studied with an ice-coated fused silica column used as a very long flow tube. Ozone destruction was found to be very slow. At 223 K and 258 K the measured reaction probabilities fall in the range 2¿10-8-4¿10-10, decreasing with increasing ozone concentration (20--1000 nbar). The observed kinetics are explained by an at least two step mechanism. The low reaction rates observed are insignificant for ozone destruction in cirrus clouds. ¿ 1999 American Geophysical Union