Photodissociation of CFClBr2 + hnu --> CFCl has been shown to occur for lambda < 274 nm (436 +/- 2 kJ mol(-1)). G3 Ab initio calculations were performed to provide estimates of Delta(f)H for CFClBr2, CFClBr, and CFCl, which were calculated to be -188 +/- 5, -43 +/- 5 and +30 +/- 5 kJ mol(-1), respectively. The dissociation energies (0 K) for sequentially breaking the C-Br bonds were calculated to be 257 +/- 5 and 183 +/- 5 kJ mol(-1), respectively. The energy required to break both C-Br bonds was calculated to be 440 +/- 5 kJ mol(-1), in excellent agreement with the experimental appearance threshold for CFCl. From the experimental appearance threshold, Delta(f)H (CFClBr2) is estimated to be -184 +/- 5 kJ mol(-1). (C) 2003 Elsevier Science B.V. All rights reserved.