The enthalpy of mixing of Fe-Ti melts is studied by high-temperature isoperibolic calorimetry at 1873 K. The experimental data on the thermodynamic functions of mixing in the melts of the system under study are used to calculate the parameters of the ideal associated solution model. This model is employed to simulate the temperature-concentration dependences of liquid Fe-Ti alloys and to find the features of change in their thermodynamic properties.