Optimization by the CALPHAD method of the thermodynamic parameters of the In-Ir system has been carried out using the experimental phase diagram data and thermodynamic properties. The numerous experimental data of the liquid phase determined in the 0 < x(Ir) < 0.35 composition range by two authors are coherent and associated with the scarce enthalpies of formation of the two intermetallic compounds allowed to optimize a set of coherent thermodynamic parameters in order to calculate the phase diagram in the In rich part. In the 0.40 < x(Ir) < 1 composition range, the phase diagram seems more complex than the schematic part extrapolated at high temperature and the agreement between the calculated diagram and this extrapolated experimental part is not satisfactory. Further experimental investigations are needed to improve the calculation in this composition range, but which are difficult because hampered by different phenomena. (C) 2011 Elsevier B.V. All rights reserved.