Using the newly constructed photoelectron-photoion coincidence apparatus associated with the chemical dynamics beamline at the advanced light source, we have performed a high resolution energy-selected kinetic energy release measurement for the dissociative photoionization process SF6 + hv --> SF5+ + F + e(-). After taking into account the center-of-mass kinetic energy release, the thermochemical threshold for this process is determined to be 14.11 +/- 0.08 eV. This value yields 18.5 +/- 1.9 and -202.9 +/- 2.2 kcal/mol for the heats of formation at 0 K for SF5+ and SF5, respectively.