NOVELTY - Method of operating a solid polymer fuel cell comprises: supplying an oxidant stream to the cathode; supplying a fuel stream to the anode; and periodically oxidant starving at least a portion of the cathode, while continuing to produce electrical power from the cell.    USE - None given.    ADVANTAGE - Periodic oxidation starvation conditions cause a change in the potential of the starved electrode and may result in the removal of electrocatalyst poisons and in improved fuel cell performance. This technique may have other beneficial effects at the electrodes, including performance improvements due to water management effects or localized heating effects at the starved electrodes. The service life of a fuel cell can be increased.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (i) a method of operating a fuel cell assembly comprising a number of fuel cells each cell having an anode and cathode. The method comprises: supplying an oxidant stream to the cathodes; supplying a fuel stream to the anodes; and periodically oxidant starving at least one of the cathodes so that cell reversal occurs in at least one of the fuel cells, while continuing to produce electrical power from the assembly;    (ii) a fuel cell apparatus comprising: an oxidant supply system for directing an oxidant stream to a cathode of a fuel cell; a flow controller for periodically interrupting the supply of oxidant stream to the cathode; and an actuator associated with the flow controller for controlling the frequency and duration of the interruptions; and    (iii) a fuel cell apparatus comprising: an oxidant supply system for directing an oxidant stream to a cathode of the fuel cell; a source of oxidant-free fluid; and a flow controller for periodically introducing pulses of the oxidant-free fluid into the oxidant stream upstream of the fuel cell.    DESCRIPTION OF DRAWING(S) - The diagram shows an apparatus which may be used to periodically reactant starve at least a portion of the electrodes in a fuel cell stack.    Stack (100)    Storage tank (102)    Compressor (110)    Reactant supply valve (120)    Reactant exhaust valve (125)    End plates (130, 140)    Reactant inlet port (150)    Reactant supply manifold (160)    Reactant flow fields (170)    Reactant exhaust manifold (180)    Controller (200)