NOVELTY - Method of purging (M1) residual hydrogen from a fuel cell stack, involves providing an air stream; providing a nitrogen stream by removing oxygen from the air stream; and passing the nitrogen stream through the fuel cell stack anode.    USE - For purging residual hydrogen from a fuel cell stack after fuel cell shutdown (claimed).    ADVANTAGE - The nitrogen-rich stream is free of oxygen (less than or equal to 2 wt.%). The adsorber is sized in such a manner that the oxygen concentration in the nitrogen stream is kept sufficiently low until after a sufficient quantity of nitrogen has flowed through the anode side of the fuel cell stack to purge the majority of hydrogen from the fuel cell stack. This prevents formation of localized corrosion cells in the fuel cell stack, thus greatly increasing stack life. The method reduces fuel cell stack cathode degradation. The adsorber improve corrosion resistance.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) reducing (M2) fuel cell stack cathode degradation involving: providing a vehicle with a fuel cell stack including an anode reactant gas flow path defined in that and a cathode reactant gas flow path defined in that and reactant is in the anode reactant gas flow path; providing a system on board the vehicle for providing a nitrogen-rich gas stream; purging the reactant in the anode reactant gas flow path comprising flowing the nitrogen-rich gas stream through the anode reactant gas flow path;    (2) method (M3) of purging residual hydrogen from a fuel cell stack anode, involving: providing an air stream; providing a first adsorbent material and a second adsorbent material; providing a first nitrogen stream by passing the air stream through the first adsorbent material and passing the first nitrogen stream through the fuel cell stack during shutdown of the fuel cell stack; providing a second nitrogen stream by passing the air stream through the second adsorbent material and passing the second nitrogen stream through the fuel cell stack during start-up of the fuel cell stack; and re-generating the first adsorbent material and the second adsorbent material by providing a hydrogen stream and passing the hydrogen stream through the first adsorbent material and thesecond adsorbent material, respectively;    (3) a purge system (10) for purging residual hydrogen from a fuel cell stack, comprising: an air flow line (12) and a hydrogen flow line (14) for delivering an air stream and a hydrogen stream, respectively, into the fuel cell stack (34); and an adsorber (16) comprising an adsorbent material provided in fluid communication with the air flow line for selectively receiving and removing oxygen from the air stream and delivering a nitrogen stream into the fuel cell stack.    DESCRIPTION OF DRAWING(S) - The figure shows a fuel cell hydrogen purge system.    purge system (10)    air flow line (12)    hydrogen flow line (14)    adsorber (16)    fuel cell stack. (34)