A system of fuel-cell stacks is provided. The system includes fuel-cell stacks, a circuit for supplying each fuel-cell stack with an oxidizing fluid, a circuit for supplying each fuel-cell stack with a reducing fluid, and a pressure-regulating device fitted to the supply circuits so as to regulate the fluid pressure in each fuel-cell stack. The pressure-regulating device includes a first line for controlling the fluid pressure and a second line for passing the fluid, these two lines being placed in parallel between an upstream channel delivering fluid from a supply circuit and downstream channels connected to each fuel-cell stack. The first line comprises a first pressure regulator for regulating the pressure in an upstream portion of the first line depending on a pressure measured downstream of a second pressure regulator placed on the second line, and the second pressure regulator is capable of matching the pressure in the downstream portion of the second line to a reference pressure, measured in the downstream portion of the first line.