A new class of hollandite Ba-Mn-Ti oxide nanocrystals was synthesized. They are synthetic min- erals exclusively composed of Ba, Ti, Mn, and O elements. The BaMn3Ti4O14.25 nanocrystals (designated BMT-134), a typical member of this newly discovered hollandite oxide group, possess a giant dielectric constant and multiferroic properties. In the present paper, electrical properties of nanocrystals of BMT-134 are studied and compared with BMT-125 (BaMn2TiO14.5). We studied the combined complex impedance and temperature dependent conductivity behaviors. The results prove that electron hopping plays a significant role in the electrical properties of the new hollandite BMT nanocrytals. In addition, the dielectric behavior and generation of ferroelectricity can be interpreted on the basis of Mott polaron theory.