The current (I) vs. voltage (U) behavior of an asymmetric ion-blocking cell, Pt, a(O2)((o)) vertical bar Bi1.46Y0.54O3 vertical bar Pt was examined, at a fixed temperature of 700 C, over a U range far exceeding the decomposition voltage U* relative to the reference oxygen activity a(O2)((o)) of the electrolytic compound Bi1.46Y0.54O3. It has been observed that until before decomposition, I vs. U behaves in a usual way, resulting in the partial electronic conductivity of the compound; decomposition starts always at a voltage a little over U*, indicating the presence of an energy barrier to decomposition; once decomposition starts at the blocking cathode, I vs. U immediately turns linear with a resistance much higher than the expectation, the total resistance of the electrolytic compound itself, indicating the presence of overwhelming anodic overpotential; decomposition of the compound proceeds as (Bi0.73Y0.27)(2)O-3 -> (Bi-0.73-delta Y-0.27)(2)O3 - 3 delta + delta(2Bi + 1.5O(2)); open-circuit voltage relaxation upon depolarization from - U(> -U*) always exhibits a time duration at -U*, indicating the reoxidation of reduced Bi. The I vs. U variation over the entire range of U as well as the decomposition kinetics of the compound are quantitatively described. (C) 2014 Elsevier B.V. All rights reserved.