The thermodynamic properties and phase diagrams of the Cd–Na and Cd–Tl binary systems have been optimized by the CALPHAD method. The liquid, hcp and bcc phases of the Cd–Tl binary system as well as the liquid phase of the Cd–Na binary system are treated with the substitutional solution model. The binary intermetallics, Cd 11 Na 2 and Cd 2 Na, are considered to be stoichiometric. Experimental information available in the literature on phase equilibria, enthalpies of mixing, enthalpies of formation and activities is employed. Self-consistent thermodynamic parameters formulating the Gibbs free energies of various phases are obtained. The calculated phase diagrams and thermodynamic properties are in satisfactory agreement with those reported experimental data.