Electrolysis of molten fluorides is one of the promising methods for the recovery and recycling of rare earth metals from used magnets. Due to the dearth of phase equilibria data for molten fluoride systems, thermodynamic modelling of LiF-DyF₃-NdF₃ system using the CALPHAD approach was carried out. Gibbs energy modelling for LiF-NdF₃ and LiF-DyF₃ systems was performed using the constitutional data from literature. Ab initio calculations were used to obtain enthalpy of reaction of LiDyF₄, an intermediate phase that is found to exist in the LiF-DyF₃ system. Differential thermal analysis was carried out for selected compositions in the NdF₃-DyF₃ system, in order to determine liquidus and solidus temperatures. The Gibbs energy parameters for the limiting binaries determined in this work is used for modelling the Gibbs energy functions of equilibrium phases in the ternary system. Selected compositions of LiF-NdF₃-DyF₃ were subjected to DTA in order to validate the calculated phase temperatures involving melt.