As one of the basic investigations on the group partitioning of actinides and lanthanides by pyrochemical reductive extraction system, their distribution behavior in a binary phase system of molten chloride and liquid zinc was studied, Generally speaking, actinides were a litte more easily reduced and extracted from the salt phase into the metal phase than lanthanides. However, the separation factors which were the differences in the distribution coefficient between actinides and lanthanides were not so large even at lower temperatures, and the group partitioning of these elements seemed less attractive in this system. The present results were much the same as those in the LiF-BeF_2/Zn system and the effect of the selection of the salt phase on the separation factors were hardly observed. For some details, the thermodynamic quantities of actinides and lanthanides in the system were calculated from the equilibrium distributions and discussed
