[en] Using the CALPHAD technique, the phase diagram and thermodynamic data of the Mg-Tl system are critically reevaluated. The liquid, hcp and bcc phases are treated with the substitutional solution model, where the excess Gibbs free energies are expressed in Redlich-Kister polynomials. All the intermetallic phases are treated as stoichiometric compounds. A self-consistent thermodynamic description of the Mg-Tl system is obtained. The calculated phase diagram and thermodynamic properties are in satisfactory agreement with the experimental results