Thermodynamics of separation of praseodymium and neodymium employing liquid low-melting metals and alloys is considered. Pr/Nd separation factors on liquid Ga, In, Bi, and Ga-In eutectic were calculated from the thermodynamic data. The obtained results are compared with the literature data on experimentally determined separation factors on “traditional” liquid metals: Bi, Zn, and Cd. It is shown that one-stage selective extraction of praseodymium or neodymium from the mixture using any of the mentioned metals is not possible. In the separation process of lanthanides from minor actinides using a chloride molten salt–liquid metal system, cerium group lanthanide fission products will be accumulated in the salt phase.