The combustion of an uncoated boron particle in an oxidizing environment is theoretically studied. Chemical reactions considered include the surfaceB-O2andB-B2O3reactions and the gas-phaseBO-O2reaction. Generalized coupling functions are identified and three limiting solutions respectively describing frozen, detached flame-sheet. and attached flame-sheet combustion for the gas-phase reaction are derived. Effects of reactivities, surface temperature, pressure. particle size, and oxide condensation are studied, while the importance of finite rale surface reactions are also demonstrated. Approximate expressions are derived for the particle burning time; the predictions compare well with the experimental data of Macek.