The triplet and singlet potential energy surfaces (PES) for O(P-3,D-1) + CF3Br reactions have been studied using the density functional method at the B3LYP level. Geometries, energies, and vibrational frequencies of CF3Br, CF3BrO ((1)A' and (3)A "), CF3OBr (1A'), CF3, BrO, CF2O, BrF, and CF2O-BrF complexes have been examined. Transition states connecting these species have been characterized and the whole potential surfaces could satisfactorily describe the O + CF3Br reactions. In the gas phase, the OBr radical is the main product on both the singlet and triplet PESs. In a condensed matrix, however, CF3OBr should be the dominant product generating from the recombination of nascent CF3 + OBr.