By means of 355 nm laser flash photolysis in the benzophenone-hydroxyanilinium ion system in acetonitrile-H2O (1 : 1, v/v) with [H2SO4] = 0.18 M, it is found that the products of H-atom abstraction by triplet benzophenone from hydroxyanilinium ion are the benzophenone ketyl and hydroxyaniline cation radicals, i.e. the NH3+ group is more reactive to H-atom abstraction by triplet benzophenone than the