An experimental study of iron-aluminium partitioning between synthetic garnet and synthetic epidote was carried out, as equilibrium was maintained in the exchange reaction expressed as follows : $Ca_3Fe_2Si_3O_12+2Ca_2Al_2AlSi_3O_12$(0H) = $Ca_3Al_2Si_3O_12+Ca_2Al_2FeSi_3O_12$(0H) Temperature has a pronounced effect on the distribution of Fe and A1 between the minerals. However, the pressure effect is not so drastic as in the exchange reaction. With increasing temperature, $Fe^{+3}$ becomes redistributed from garnet into epidote, whereas A1 becomes redistributed from epidote into garnet. This is in line with the general principle of phase correspondence, as the temperature increases the more electropositive metal aluminium redistributes from epidote into garnet. The agreement between the experimental results of this study and the natural samples suggests that $K_D=X^{Ep}_{Fe}/X^{Gr}_{Fe}$ may be a useful geothermometer for metamorphic rocks containing garnet and epidote that are close to binary Fe-A1 compounds.