A method for chemically destroying magnetic data carriers. Recorded data are irretrievably eliminated and cannot be re-read. The carriers include aluminium or its alloys and ferromagnetic materials. They undergo a digestion reaction with an aqueous solution of a digesting mixture including: a) hydrochloric acid and (V)nitrate of one or more alkali metals, alkaline earth metals, rare earth metals and ammonium; or b) nitric(V) acid and chloride of one or more alkali metals, alkaline earth metals, rare earth metals and ammonium. The product of the reaction is an aqueous solution having aluminium hydroxide and chlorides and (V)nitrates of metals contained in the ferromagnetic metals and gaseous products of the reaction. Acidic salt solutions are utilized in a sewage treatment plant. Gaseous products including hydrogen and nitrogen oxides, after diluting with nitrogen, are directed to the atmosphere through an absorption system.