A new high-temperature calorimeter was used to study the enthalpies of mixing of nickel-rich Al-Ni melts (mole fraction of Al<0.22) at 1823 K. Concentration dependencies of the partial and integral enthalpies of dissolution of aluminium were obtained experimentally. The model of quasi-ideal associated solutions and ASSOL-2 original software were used to treat and evaluate all available thermodynamic data for liquid AI-Ni system. The description of thermodynamic properties of Liquid Al-Ni alloys in a wide concentration and temperature intervals was obtained.