Foam fire extinguishing agent

A foam fire extinguishing agent comprising about 0.3 to about 50% by weight of one or more alkyl acid phosphates and/or one or more salts thereof, about 0.05 to about 10% by weight of one or more amphoteric surface active agents, about 0.001 to 0.3% by weight of one or more fluorocarbon-type surface active agents, and as the balance of said agent an aqueous solution, said one or more amphoteric surfactants being selected from the group consisting of compounds represented by the formula:

• ##STR8## wherein R' is an aliphatic hydrocarbon group containing 4 to 18 carbon atoms;
• X' is a hydrogen atom, an aliphatic hydrocarbon group containing 1 to 18 carbon atoms or a CH.sub.2 CH.sub.2 COOM group;
• and M is a hydrogen atom, a sodium atom, a potassium atom, an NH.sub.4 group, a (C.sub.1 -C.sub.6)alkylamino group or a (C.sub.1 -C.sub.6)alkanolamino group;
• and said one or more fluorocarbon-type surfactants being selected from the group consisting of C.sub.8 F.sub.17.sup. - OC.sub.6 H.sub.4 SO.sub.3 Na, C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)CH.sub.2 COOK, (C.sub.2 F.sub.5).sub.2 (CF.sub.3)C.multidot.CH.dbd.C(CF.sub.3)SO.sub.3 NH.sub.4 and [C.sub.8 F.sub.17 .multidot.SO.sub.2 NH(CH.sub.2).sub.3 .multidot.N(CH.sub.3).sub.3 ]I.