In this paper the behaviour of bipolar membranes at very high current density is discussed. Current-voltage curves are determined, both for the Tokuyama Soda BP-1 and the WSI Technologies bipolar membrane. The current-voltage curves are characterised by an inflection point at which a drastic increase in resistance occurs. The inflection point is due to a limitation in the water supply into the bipolar membrane. The bipolar membranes are found to be damaged by applying current densities near and above the current density belonging to the inflection point. Measurements with the WSI membrane show that this damage primarily affects the anion exchange layer of the bipolar membrane. Furthermore, in this paper a qualitative comparison is made between calculated and experimental current-voltage curves.