A bleaching composition is described that includes a peroxygen compound such as sodium perborate, an oxygen transfer agent in the form of a quaternary imine salt and a bleach precursor. The quaternary imine salt at relatively low concentrations enhances the activity of the precursor. A method for bleaching substrates is also provided, especially a method for cleaning fabrics. The preferred quaternary imine salt has the structure: ##STR1## wherein: R.sup.4 may be a substituted or unsubstituted radical selected from the group consisting of hydrogen, aryl, heterocyclic ring, alkyl and cycloalkyl radicals;R.sup.5 and R.sup.6 may be a substituted or unsubstituted radical selected from the group consisting of hydrogen, aryl, heterocyclic ring, alkyl, cycloalkyl, nitro, halo, cyano, alkoxy, keto, carboxylic and carboalkoxy radicals; andX.sup.- is a counterion stable in the presence of oxidizing agents.