Ceramic solid solutions Bi4(V1 - xCux)2O11 - y with x = 0 ÷ 0.2, Δx = 0.02, have been prepared by the solid state reactions. The samples were studied by the DTA/DSC, X-ray diffraction and dielectric spectroscopy methods. Concentration and temperature stabilization regions of the polymorphous α, β and γ′ modifications have been defined. Decreasing of the ferroelectric α-β phase transition temperature, enlargement of the temperature interval of thermal hysteresis while increasing in temperature of the transition between tetragonal γ′ - γ phases have been revealed. Dielectric measurements gave an indication on the effect of the domain walls "pinning" by oxygen vacancies inherent to the bismuth vanadate based compositions. Copyright © Taylor & Francis Group, LLC.