The charge injection limits of a Pt electrode using 0.2 ms charge balanced, biphasic current pulses ranged from 50 to 150 microC/cm2 geometric if the potential excursions of the electrode are kept below those at which H2 or O2 is produced. These charge densities are three to ten times smaller than the currently accepted value based on earlier experiments in which the reversible surface reactions were fully utilized and the pulse widths were longer.