Solid compositions comprising an alkali metal borohydride and an ammonium salt, which generate hydrogen gas upon combustion

The invention relates to solid compositions that decompose by generating hydrogen according to a self-sustaining combustion reaction after initiation of this reaction by an appropriate heat source. These compositions comprise an alkaline borohydride and an oxidizing mineral ammonium salt of formula NH₄Y in which Y represents a group consisting solely of nitrogen and oxygen. The ratio of the weight content of alkaline borohydride to the weight content of salt of general formula NH₄Y is between 1 and 4. This makes it possible to obtain high hydrogen mass yields, on the order of 8 to 14%, which makes it possible to reduce the size and weight of hydrogen generators used in certain systems, in particular in proton exchange membrane fuel cells.