Abstract: In order to improve the flame-protection effect without substantially impairing the mechanical properties of the articles covered with the flame protection agent, the flame protection agent is provided with a compound in a proportion by weight of 7.5 to 30% which contains at least one sulfo group or sulfonium ion. This compound is preferably a water-soluble ammonium salt. As binder there is used an aqueous solution or aqueous dispersion of an organic material, particularly of an acrylate or of a polymer or copolymer having a base of acrylic acid ester. It is particularly advantageous if substantially open-cell polyurethane foam having a base of polyether is impregnated with such a flame-protection agent which contains an ammonium salt of an aminosulfonic acid in a proportion of about 12%. Polyurethane foams impregnated in this manner are particularly well suited for use in cushionings of articles or in premises for which class B1 fire protection is required.