The invention is directed to a fire-extinguishing composition comprising an oxidant, a secondary fuel and a phenol-formaldehyde resin, wherein the phenolformaldehyde resin molecule contains more than 3 aromatic ring structures and its use to extinguish a fire, especially a fire in an enclosed space. The invention is also directed to a process to prepare such a composition and to the use of the composition to extinguish a fire by an aerosol which is formed during burning of the composition.