In the present communication, it is suggested a new microscopic approach for the description of the effects of an external direct current (dc) electric field in the magnetic, polarization and spectroscopic characteristics of molecular crystals containing cyanide-bridged Fe-Co clusters as structural units. The developed approach takes into account the intracluster electron transfer, the intercluster cooperative electron-deformational interaction, the Heisenberg exchange interaction in each Fe-Co pair as well as the external dc electric field oriented along the line connecting the Fe and Co ions in the cluster. In the states of configuration ls-FeII–ls-CoIII, (ls-low spin, hs-high spin) the dipole moment is vanishing, while the states of configurations ls-FeIII–ls-CoII and ls-FeIII–hs-CoII possess a dipole moment. Since the states of configurations ls-FeII–ls-CoIII and ls-FeIII–ls-CoII are coupled by electron transfer, the electric field suppresses this intracluster transfer, leading thus to the appearance of a non-vanishing cluster dipole moment. The larger the parameter of electron transfer, the stronger intensity of the external electric field is needed to suppress the electron tunneling and to produce crystal polarization. Insofar as the tunnel states of the cluster represent a linear superposition of the localized states, which arise from configurations ls-FeII–ls-CoIII and ls-FeIII–lsCoII and possess different dipole moments, the energy gap between these states depends on the direction of the external electric field, thus leading to a different temperature dependence behavior of the mean dipole moment and Mössbauer spectra for opposite directions of the field. Finally, it should be mentioned that crystals containing binuclear Fe-Co clusters as structural units do exist and have been recently reported [1]. Under certain conditions, these systems demonstrate charge transfer induced spin transitions and thus, the manipulation by their properties with the aid of an external electric field is expected to be possible.