Polymer　electrolyte　membrane　fuel　cell　(PEMFC)　displays　great　potential　to　replace　internal　combustion　engine　in　the　field　of　powering　next　generation　vehicle　according　to　its　special　advantages,　i.e.,　zero/low　emissions,　low　operation　temperature,　and　high　energy　density,　etc.　To　feed　vehicular　application,　PEMFC　is　required　to　meet　varied　driving　conditions　as　well　as　road　situations,　which　are　complicated　and　unpredictable.　In　particular,　the　transient　load　(such　as　acceleration　and　uphill　start　conditions)　applied　to　PEMFC　may　cause　oxygen　insufficient,　and　even　starvation　since　the　required　power　demand　is　much　higher　than　the　generated.　The　oxygen　starvation　results　in　low　efficiency　of　PEMFC　and　also　do　harm　to　the　lifetime　of　PEMFC.　Therefore,　in　order　to　protect　PEMFC　from　oxygen　starvation　as　well　as　to　improve　PEMFC　efficiency,　air　supply　system　control　of　PEMFC　is　necessary.　In　this　study,　oxygen　excess　ratio　regulation　for　air　supply　system　control　of　PEMFC　is　developed　based　on　nonlinear　sliding-mode　control.　Primarily,　the　oxygen　excess　ratio　is　defined　in　Matlab/Simulink　to　apply　to　design　the　sliding-mode　controllers.　Subsequently,　the　non-linear　sliding-mode　manifold　is　selected　to　cope　with　the　high　nonlinear　characteristics　of　the　PEMFC　system,　and　to　improve　the　robustness　against　external　disturbance.　To　test　the　proposed　non-linear　sliding-mode　control　approach,　a　comparison　study　is　then　carried　out　by　contrasting　normal　sliding-mode　manifold　as　well　as　linear　sliding-mode　manifold.　Experimental　validation　is　finally　implemented　to　confirm　that　the　proposed　method　is　suitable　for　oxygen　excess　ratio　regulation.