The present invention relates to a powdery composition comprising a chloride selected from sodium chloride, magnesium chloride, calcium chloride, potassium chloride and mixtures thereof; metal particles of zinc and/or of aluminum and/or a metal salt; and optionally another corrosion inhibitor, and its method of preparation. It also relates to the use of metal particles in such compositions to protect steel or iron structures against the corrosion induced by chloride ions.