Abstract: Solid Peroxyacid bleach precursor compositions are provided in which the external surfaces of a particulate peroxyacid precursor material is treated with from 2% to 20% by weight of a solid organic acid compound of Mpt>30.degree. C. and an aqueous solubility of at least 20 g/100 g water at 20.degree. C. The bleach precursor material, when so treated, perhydrolyses after 3 minutes in a standard test at 20.degree. C., to at least 90% of the extent of the untreated bleach precursor material under the same conditions. Preferred organic acid compounds are monomeric aliphatic hydroxycarboxylic and polycarboxylic acids such as citric, lactic and glycolic acids. Detergent compositions containing the treated peroxyacid bleach precursor particulates are also disclosed.