The distributions of current and potential on the tubular positive plate have been studied by measuring the IR drop in the H2SO4 solution between the positive and negative plates. It is found that lower polarization and higher current appear in the upper part of the plate. But the resistance of the active mass develops very rapidly at the top and at the bottom of the plate. This leads to very high polarization and low current in these regions in the later stage of the discharge. And it is interesting to find that the potential difference up and down the plate is mainly caused by the interface resistance between the active mass and the spine. (C) 2003 Elsevier Science B.V. All rights reserved.