Proton　exchange　membrane　fuel　cell　(PEMFC)　experiences　inevitably　performance　decay　due　to　various　mechanisms.　Among　those,　carbon　corrosion　is　extremely　detrimental.　In　this　study,　an　accelerated　stress　test　(AST)　is　conducted　to　a　single　cell　to　mimic　the　conditions　when　carbon　corrosion　occurs.　The　cell　performance　is　characterized　intermittently,　and　the　experiment　results　show　although　electrochemical　active　area　(ECA)　decreases　continuously　from　beginning-of-life　(BOL)　due　to　carbon　corrosion　at　catalyst　layer　(CL),　kinetic　degradation　is　not　apparent　until　AST　3　h.　After　that,　kinetic　loss　increases　progressively,　while　ohmic　loss　increases　continuously.　However,　due　to　decrease　of　water　generation　under　voltage-controlled　condition,　or　enhancement　of　water　removal　by　phase　change　induced　flow　(PCI)　under　current-controlled　condition,　the　mass　transport　is　slightly　improved　at　later　period　of　AST.　To　confirm　such　variation　of　mass　transport　loss,　cell　performance　and　EIS　are　measured　at　reduced　air　relative　humidity　(RHc)　and　reduced　air　flow　rate.　Both　cell　performance　and　EIS　results　show　that　in　a　degraded　fuel　cell,　reduced　air　RHc　and　higher　air　flow　rate　are　beneficial　to　cell　performance.　Hence,　more　sophisticated　water　management　strategies　for　PEMFCs　is　recommended　for　different　periods　in　their　lifetime　for　a　fuel　cell　stack.