Nitrile activators, such as N-alkyl ammonium acetonitrile activators, are combined with a source of active oxygen as cleaning and bleaching compositions. Preferred activator embodiments of the invention include salts of N-methyl morpholinium acetonitrile, N-butyl morpholinium acetonitrile, N-hexyl morpholinium acetonitrile, and N-octyl morpholinium acetonitrile. A particularly preferred activator embodiment is an N-methyl morpholinium acetonitrile salt. The nitrile and active oxygen react to form a bleaching agent which is applied to a stain on an article. The treated stain is contacted with dense gas so as to provide substantially non-aqueous stain removal. One embodiment is a composition in which the nitrile and active oxygen are disposed in the dense carbon dioxide.