Abstract: The Ni-Ga system was assessed using the CALPHAD technique. The thermodynamic behav-iour of the ordered phases (Li₂-Ni₃Ga and H₂-NiGa) were described by the sub-lattice model, and the order-disorder transformation of fcc-(Ni) and Li₂-Ni₃Ga phase was considered in the assessment. The solution phases (liquid, fcc-Ni) were modeled with the Redlich-Kister equation. The other 5 intermetallic compounds were treated as stoichiometric phases.