A technique was described for measuring thermal vacancy concentrations. The densities of specimens, quenched from various temperatures in order to freeze in thermal vacancies, were deduced from room-temperature lattice parameter and bulk density measurements. The 2 sets of density data were extrapolated to a quenching temperature of 0K, and were adjusted so as to match at that temperature. From the adjusted density values, the vacancy concentrations were calculated as a function of temperature. The vacancy formation enthalpy for stoichiometric FeAl was found to be 0.51eV. A comparison with published experimental and theoretical formation enthalpies revealed a considerable uncertainty in measuring and interpreting the formation energy. The formation energy for thermal vacancies in stoichiometric FeAl was believed to be between 0.5 and 0.8eV. A Technique for Measuring Thermal Vacancy Concentrations in Stoichiometric FeAl. J.H.Schneibel, L.M.Pike: Intermetallics, 2004, 12[1], 85-90