We report on the dielectric properties of bismuth aluminate and gallate with Bi:Al(Ga) ratio of 1:1 and 12:1 prepared at high temperature and ambient pressure. These compounds crystallize in a noncentrosymmetric body-centered cubic structure (space group I23) with a ∼ 10.18 Å rather than in the perovskite structure. This cubic phase is related to the γ - Bi2 O3 structure which has the actual chemical formula Bi243 + (Bi3 + Bi5 +) O40 - δ. In the aluminates and gallates studied by us, the Al and Ga ions are distributed over the 24 f and 2 a sites. These compounds exhibit ferroelectric hysteresis at room temperature with a weak polarization. © 2006 Elsevier Ltd. All rights reserved.