A bleaching agent is described particularly effective for low temperature bleaching of laundry while avoiding concomitant dye damage of bleach-sensitive dyed fabrics. The bleaching agent comprises particles of monoperoxyphthalic acid (MPPA) and/or a water-soluble salt thereof, said particles being at least partially coated with an effective amount of a substantially aliphatic fatty acid mixture comprised of at least 16% and no more than about 40%, by weight, of fatty acids having a chain length of from 20 to 22 carbon atoms, said mixture being substantially free of fatty acids having less than 14 carbon atoms.