The gas phase HBr-catalyzed reaction UF6 + SiH4 at room temperature and its kinetic mechanism were investigated. It was found that this catalyzed reaction followed the first-order kinetics, and the reaction rate constant was proportional to the concentration of catalyst HBr, e.g. the measured rate constants were 0.75 x 10(-3), 1.58 x 10(-3) and 3.00 x 10(-3) s(-1) at the respective concentrations of HBr at 0.5 x 133.3, 1.0 x 133.3 and 2.0 x 133.3 Pa. The proposed kinetic mechanism of the HBr-catalyzed reaction was in good accordance with the measured results.