APPARATUS AND METHOD FOR CONTROLLING FUEL CELL STACK

An apparatus and a method for controlling a fuel cell stack are provided to improve the performance (output) of the fuel cell stack that has suffered from deterioration. The performance is improved by adjusting a stoichiometric ratio (SR) of air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on the basis of an open-circuit decay time (ODT) indicating a time taken for a cell voltage to be reduced from a reference voltage to a threshold voltage when the supply of air to the fuel cell stack is cut off.