A chlorine dry bleach having as its essential components trichloroisocyanuric acid and as a chemical stabilizer therefor hydrated sodium dichloroisocyanurate the water content of which is from about 7 to about 14%. The composition has excellent storage properties and generally good thermal stability and exhibits higher water solubility than trichloroisocyanuric acid alone. It can be used in any application calling for a source of active chlorine such as in water supplies for preventing the growth of pathogenic bacteria or as a bleach in detergents and as a sanitizing agent.
