Powder mixtures of a-Bi 2 O 3 (bismite) and monoclinic m-ZrO 2 (baddeleyite) in the molar ratio 2:3 were mechanochemically and thermally treated with the goal to examine the phases, which may appear during such procedures. The prepared samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), electrical measurements, as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanochemical reaction leads to the gradual formation of a nanocrystalline phase, which resembles d-Bi 2 O 3 , a high-temperature Bi 2 O 3 polymorph. Isothermal sintering in air at a temperature of 820 1C for 24 h followed by quenching to room temperature yielded a mixture of ZrO 2 -stabilized b-Bi 2 O 3 and m-ZrO 2 phases, whereas in slowly cooled products, the complete separation of the initial a-Bi 2 O 3 and m-ZrO 2 constituents was observed. The dielectric permittivity of the sintered samples significantly depended on the temperature. The sintered and quenched samples exhibited a hysteresis dependence of the dielectric shift, showing that the ZrO 2 -doped b-Bi 2 O 3 phase possess ferroelectric properties, which were detected for the first time. This fact, together with Rietveld refinement of the b-Bi 2 O 3 /m-ZrO 2 mixture based on neutron powder diffraction data showed that ZrO 2 -doped b-Bi 2 O 3 has a non-centrosymmetric structure with P 42 1 c as the true space group. The ZrO 2 content in the doped b-Bi 2 O 3 and the crystal chemical reasons for the stabilization of the b-Bi 2 O 3 phase by the addition of m-ZrO 2 are discussed.