1. Niobium pentoxide in the solid state is an electronic semiconductor, whose energy of activation of current carriers, δE, in the region of its melting point is equal to 1.56 eV. 2. At room temperature, Nb2O5 exhibits thermal ionic polarization, which grows up to a certain temperature and is characterized by the formation of a unipolar-conduction barrier layer. 3. The electrophysical properties of Nb2O5 depend upon the oxygen partial pressure in the surrounding atmosphere.