The enthalpies of formation of the title compounds have been determined by simultaneous least-squares solution of a thermochemical network containing 28 experimental measurements extracted from the literature. The new enthalpies differ considerably from the older tabulated values and now show a high degree of internal consistency achieved through excellent agreement with newer experiments, as well as older calorimetric determinations. The fitted values are: ΔHf298°(CF3) = −111.3 ± 0.5 kcal/mol (−110.6 ± 0.5 kcal/mol at 0 K), ΔHf298°(CF3H) = −165.6 ± 0.5 kcal/mol (−163.9 ± 0.5 kcal/mol at 0 K), ΔHf298°(CF3Cl) = −169.5 ± 0.7 kcal/mol (−168.3 ± 0.7 kcal/mol at 0 K), ΔHf298°(CF3Br) = −155.3 ± 0.5 kcal/mol (−152.4 ± 0.5 kcal/mol at 0 K), ΔHf298°(CF3I) = −140.1 ± 0.5 kcal/mol (−138.7 ± 0.5 kcal/mol at 0 K), ΔHf298°(C2F6) = −321.3 ± 0.8 kcal/mol (−319.3 ± 0.8 kcal/mol at 0 K), and ΔHf298°(CF3CN) = −118.4 ± 0.4 kcal/mol (−117.5 ± 0.4 kcal/mol at 0 K). Theoretical calculations at the Gaussian-3 (G3) level of theo...