The invention is directed to a solid, porous material, suitable for generating nitrogen gas, said material having a porosity of 20 to 75 vol.%, and a composition comprising, based on the weight of the material of 60 to 90 wt.% of sodium azide, 0.1 to 20 wt.% of an inert chemical coolant based on at least one inorganic salt having a heat capacity of at least 1400 J/K/kg, 0.1 to 20 wt.% of modifying agent selected from metal oxides and metal carbonates, and a binder, selected from the group consisting of at least one alkali metal silicate, preferably waterglass, or a poly-tetrazole, in an amount of between 3 and 15 wt.%.