The method is for continuously producing compressed-air foam, notably for fire fighting or for decontamining, by supplying both compressed air and a mixture of water and at least a foaming agent to a foaming chamber (5) outputting foam to a nozzle (9) via a pipe (8). The mixture of foam agent and water and the compressed air are each continuously supplied to the foaming chamber (5) at a constant pressure and at a constant volume flow rate, e.g. by means of pressure regulators (1, 2) and of flow rate regulators (3, 4). The foam pressure is regulated at the outlet of the foaming chamber (5) for maintaining the foam mixing pressure in the foaming chamber constant, preferably by a self-operating valve (6). The foaming chamber can advantageously be of a static type comprising sieves.