Abstract: According to a first aspect, the present invention relates to a method of controlling a fuel cell, comprising a step of controlling the fuel cell electric efficiency per unit of active surface area by checking and/or adjusting the current density produced in the fuel cell per unit of active surface area. According to another aspect, the present invention concerns a fuel cell suitable for obtaining an electric power output, which comprises, among the other things, control means of the electric efficiency of the fuel cell including means suitable for checking and/or adjusting the current density produced in the fuel cell per unit of active surface area.