Two potential energy surfaces 1 2A1 and 1 2B1 for linear geometry of F-H-Br system have been computed with aug-cc-pVQZ basis set using dynamically weighted state averaged MCSCF followed by MRCI-F12 method. State 1 2A1 has smaller barrier height (3.49 kcal/mol) than 1 2B1. (13.6 kcal/mol). The latter has deep van der Waals well in Br-HF valley (2.12 kcal/mol).