This paper proposes a sliding mode controller for air supply subsystem on a PEM Fuel Cell system in order to regulate and replenish the oxygen depleted from the Fuel Cell cathode during stack current demands. According to the stack current, a reference value of air flow was obtained with the steady-state analysis of oxygen excess ratio (OER). To ensure the system working in the reference value of OER, a control scheme includes a sliding mode controller was proposed to adjust the air flow rate provided by the air compressor. Simulation results show that the control methods has good responses against disturbances and uncertainties
