The enthalpies of formation of liquid BaF2-KF-ZrF4 and BaF2-LiF-ZrF4 ternary mixtures were measured calorimetrically at 1173 K. The mixing procedures used, the "direct drop" or "indirect drop" methods, were selected in accordance with the physicochemical properties of the systems. The results are compared with those previously obtained for the liquid BaF2-NaF-ZrF4 ternary system. For all systems, enthalpies of mixing are found to be strongly exothermic; these results are analysed in terms of formation of complex ions in the liquid mixtures.