The gas phase reactions BrONO2 and ClONO2+O3→Products (k1 and k3) were examined at 235¿2 K and 700 Torr N2 using a Fourier transform infrared spectrometer coupled to a temperature regulated long path absorption cell. The loss of BrONO2 and ClONO2 were measured to be independent of the O3 concentration yielding k1<1¿10-20 cm3 molecule-1 s-1 and k3<4¿10-21 cm3 molecule-1 s-1. ¿ 1998 American Geophysical Union