The dielectric relaxational processes (low-frequency electric field absorption, or dielectric losses) in mixed-valence clusters are investigated by using a binuclear cluster example. We show that study of these processes can provide valuable information about electron transfer. In particular, study of the frequency-dependent loss for a range of temperatures permits (in the Robin/Day classes I and II) experimental estimation of the tunneling and electronic asymmetry parameters. The effective activation energy can also be found from the temperature dependence, and this, in turn, fixes the reorganization energy.