The molar enthalpy of formation of the [Ir-In] liquid alloys [Δ m i x H m o ] corresponding to the reaction, at T e and p o :a In ( l i q ) +b Ir ( l i q ) ->In x Ir ( 1 - x ) ( l i q ) was determined on the following temperature and molar fraction ranges 1175<T e /K<1589 and 0<x<0.26 (where x is the iridium molar fraction x I r ), respectively, with a fully automated high temperature calorimeter. In these temperature and molar fraction ranges, the enthalpy of formation is negative and not temperature dependent. As for the other (TM-sp) binary systems previously studied, assuming suitable the Redlich-Kister relation, the enthalpy of mixing could be described as follows (in kJ.mol - 1 ):Δ m i x H m o =x.(1-x)ξ(y)with ξ(y)=-74.27+18.51y+27.74 y 2 -15.28 y 3 and y=(x I r -x I n ). In this case, the coordinates of the minimum are estimated to be at Δ m i x H m o =-19+/-1 kJ.mol - 1 and x=0.45+/-0.01. The limiting partial molar enthalpy of mixing of iridium, deduced from experiments performed at 1154 K, is:Δ m i x h m o (Ir supercooled liquid in ~ liq In)=-50+/-2 kJ.mol - 1 .The integral and limiting partial enthalpies of mixing have been compared with the data predicted by Miedema and co-workers. The trend of the Δ m i x H m o =f(x) diagrams obtained at the lower temperature (below 1175 K and between 1200 and 1300 K) allow us to conclude that the solid phases IrIn 3 and IrIn 2 are in equilibrium with the liquid phase. For three compositions (x=0.186, 0.25 and 0.33), the molar heat capacities have been measured between 423 and 763 K. These results are compared with the values calculated with the Neumann-Kopp law. The weak thermal effect appearing in the Cp o =f(T) graph with the alloy x=0.186 can be due to a change of structure. So, some information concerning the [Ir-In] equilibrium phase diagram (eutectic, peritectic and liquidus temperatures) was obtained. Thus, in the In-rich region, a preliminary shape of the liquidus of the [Ir-In] system has been proposed. Finally, thermodynamic results obtained under the same condition, on the one hand, for the Co-In system and, on the other hand, for the Ir-In system, have been compared: the existence of a liquid-liquid miscibility gap at high temperature could also be assumed for this last system.