Understanding the detailed mechanism of boron combustion in;the presence of fluorine has important consequences to the development of energetic materials. From a recently proposed reaction mechanism,(1) one of the dominant reactions for which very little kinetic or mechanistic information is available is HBO + F --> FBO + H. Ab initio multiconfigurational methods have been used to study two reactive pathways stemming from the reactants HBO + F. These are HBO + F --> HF + BO and HBO + F --> H(F)BO --> H + FBO. The optimized structures and harmonic vibrational frequencies of the stationary points are reported, and other features of the potential energy surface of HBOF are discussed. Furthermore, the rate constants were calculated by using transition-state theory and variational transition-state theory. For reaction 2, Delta H-R = -20.7 kcal/mol, E(A) = 2.7 kcal/mol, and k(2)(T) = (5.08 x 10(-16))T-1.77 exp(-1666/T) cm(3) molecule(-1) s(-1). Reaction 3a is two and a half times more exothermic than reaction 2 and proceeds without a barrier. For this reaction, Delta H-R = -56.5 kcal/mol and k(3a)(T) = (4.22 x 10(-14))T-0.98 exp(353/T) cm(3) molecule(-1) s(-1). Reaction 3b is endothermic with Delta H-R = 9.9 kcal/mol, E(A) = 13.0 kcal/mol, and k(3b)(T) = (7.00 X 10(13))T--0.01 exp(7817/T) s(-1). These calculations predict that reaction 1 proceeds through the formation of an H(F)BO complex which dissociates to form FBO + H. At low temperatures, the complex formation dominates the HBO + F reaction, but at temperatures exceeding 1500 K it competes with the abstraction pathway. These findings have important implications to the development of the reaction mechanism because they predict the formation of a complex which was not previously included in the model, and they provide kinetic parameters that are not available experimentally.