Abstract: An improved dry powder composition for use in aqueous solution in the bleaching and sanitizing of fabrics, which will cause minimal fabric or fabric dye damage upon direct contact of the concentrated composition with damp or wet fabric. The composition includes a first component comprising a dry dihalohydantoin, which in aqueous solution provides a source of available bleaching and sanitizing chlorine; and a second component comprising an inhibiting system in an effective amount to inhibit the activity of available chlorine from the first component such that fabric or fabric dye degradation is beneath a predetermined level when the concentration of the first component of the composition is above saturation with respect to the aqueous solvent. The inhibiting system comprises 5,5-dimethylhydantoin, and one or more dry acidifying agents which function to buffer a 50% aqueous solution/suspension of said composition to a pH of 5.0 or below.