System for storing fuel in a handheld device

System for storing fuel in a handheld device that has a housing (11) made up of a set of pieces that define a receptacle inside which are housed a plurality of electronic circuits (23) and a fuel cell stack. Said fuel cell stack transforms the chemical energy stored by a fuel into electrical energy so that the fuel is contained in a container suitable for occupying a free space (22) between the electronic circuits (23) and the housing (11).