DescriptionSolubility of nickel in liquid Mg–Al alloys has been measured in the temperature range 650–900°C for 1–10% aluminium content. Comparison of nickel solubility in pure magnesium with solubility in Mg–Al alloys shows a marked reduction of nickel solubility with a small addition of aluminium. SEM analysis shows that the precipitated phases in equilibrium with the melt are AlNi and Al3Ni2 with the latter becoming more dominant as the aluminium concentration increases. The solubility of Ni in the melt in equiIibrium with AlNi is given according to the dissolution reaction AlNi = Al + Ni. Thermodynamic parameters optimised using the least square method are presented.