A metal-containing composition substantially comprising (i) at least one water soluble metal compound which forms metal ions when dissolved in water, (ii) at least one metal ion modifier as herein defined, (iii) at least one acid, and (iv) water said composition having a pH of less than 6 and an electrolytic potential in excess of 10 millivolts. Such compositions have uses in the prevention and/or treatment of pathogenic disease or disorder, as foodstuff supplements, in the treatment by disinfection of meat and other foodstuffs, in the coating, sealing and plating of metals, and treatment of water and sewage.