Switchable molecular materials represent one of the hot topics of material science due to their promising applications in spintrnnics and quantum computing. This class of materials is characterized by the possibility to shift between two or more stable states in response to the external stimuli such as light, temperature, pressure or applied magnetic and electric fields . Complexes of Co, Mn, Fe, Rh, fr and Cu with ligands derived from substituted o-benzoquinones demonstrating valence tautomerism represent a class of materials whose optical, strnctural and magnetic characteristics can be changed by external stimuli. In the present communication we examine the effects of the applied de electric field in the optical, magnetic and polarizabilty characteristics of cobalt valence tautomeric complexes. For + Co-comrlexes the interconversion 2 is described by the equation: [low-spin - Co3 (N/\N)(sq )(cat2-)]+-+[high-spin-Co +(N/\N)(sq1-)2], where N/\N is a chelating diiminium ligand, the ligands semiquinone (sq) and catecholate (cat) can be obtained from o- quinone by an addition of one and two electrons to the empty n * molecular orbital. The model proposed takes into account ligand-metal and ligand-ligand electron transfer, intrnmolecular magnetic exchange interactions, the interaction of the Co-ion with full symmetric vibrations of the nearest smTOlmding as well as the interaction of the complex with the external electric field. In order to describe properly the changes in the intrinsic characteristics of the complex under action of the external electric field the vibronic problem of pseudo-Jahn-Teller effect is solved. The obtained energy levels and co1Tesponding vibronic(hybrid) wave-functions are used for the calculation of the shape of the optical band in the near infrared range as well as of the temperature and field dependence of the molecular magnetic and mean dipole moments. The latter reflects the degree of polarizability of the Co-complex. It has been demonstrnted that the external electric field suppresses the electron ti·ansfer and leads to the decrease of the magnetic moment of the complex with increase in the field intensity. A significant fall in the intensity of the optical band of the complex in the infrared region can also be observed when the intensi of the electi·ic field i .1 . Thus, b la ·n with the direction and intensity of the electi·ic field the critical temperatme for the valence tautomeric interconversion, the polarizability, optical and magnetic characteristics can be significantly changed. This offers the lmique chance of conti·olling the optical and magnetic response at the atomic scale by electrical means.