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