A system and method for controlling operation of a fuel cell system of a fuel cell vehicle, to reduce an amount of heat generated by one or more heat sources in the fuel cell system, are provided. The method comprises obtaining a value of power output of the fuel cell system, the value indicating a power demand from the fuel cell system during operation of the vehicle; and adjusting a value of a target coolant inlet temperature of a coolant at a coolant inlet of the fuel cell stack to vary between a first target temperature level and a second target temperature level, in dependence on the value of the power output, to optimize a duration of time during which the target temperature is different from the first target temperature level and to optimize a value of one or more parameters related to operation of the fuel cell system.