A simple model of a fuel cell stack revealed a novel effect: the spot of low current (resistive spot) in one of the cells is electrostatically mirrored by the bipolar plates in the adjacent cells. The governing equation for stack potential is derived and analysis of this equation leads to a simple formula for the characteristic length of mirroring. This length increases with the cross-sectional size of the stack and with the resistivity of the bipolar plate; it decreases, however, with the growth of cell resistivity. The physics of mirroring and related mechanism of stack aging are discussed. (c) 2007 The Electrochemical Society.