The Mo-Ni-V system has been assessed by means of the CALPHAD (CALculation of PHAse Diagram) approach. The binary system Ni-V was reassessed by considering all available thermochemical and phase diagram data. According to the crystallographic data, the a intermediate compound is described by a three-sublattice (Ni,V)(10)V-4(Ni,V)(16). Calculated phase diagram and thermochemical properties of the Ni-V system showed a good agreement with experimental data. A set of self-consistent thermodynamic parameter for the Mo-Ni-V system was obtained by considering the phase diagram data in the ternary system. Comprehensive comparisons between the calculated and measured phase diagram and thermodynamic data showed that the experimental information was satisfactorily accounted for by the present thermodynamic description.