The photoelectrochemical oxidation of aqueous sulfite on composite electrode films comprising titania particles as the dispersed component and nickel as the matrix (Ni-TiO2) is described. These composite. films exhibit unusual photocurrent enhancement for sulfite oxidation relative to the corresponding neat TiO2 films containing no nickel. Both the morphology of the composite films and their surface chemical composition (Ni:Ti ratio) are shown to play a role in the photocurrent enhancement mechanism. Two potential domains for sulfite photooxidation separated by the onset of dark oxidation of sulfite by the nickel matrix itself are considered.