The uptake coefficient gamma of HOBr on the ice surface from 190 to 239 K has been investigated in a flow reactor interfaced with a differentially pumped quadrupole mass spectrometer, gamma of HOBr on ice is in the range 0.11-7 x 10(-3) at 190-218 K and is in the range 2 x 10(-3) to 6 x 10(-4) at 323-239 K. The desorption temperature Td Of HOBr on the ice film was determined. Td increases with the HOBr exposure. The Monte Carlo simulation was used to shed light on the nature of the desorption and gas-surface interactions. This study extends our investigations to the reaction probability of the HOBr + HCI reaction. The reaction probability ranges from 0.05 to 0.23 at 190 K and 0.004 to 0.19 at 222 K as a function of P-HCl which varies from 1.3 x 10(-7) to 8.8 x 10(-6) Torr and 4.2 x 10(-7) to 1.5 x 10(-5) Toll, respectively, Kinetic analysis indicates that the heterogeneous reaction of HOBr + HCI follows the Langmuir-Hinshelwood type.