Diphenyl selenide (kq = 2.5 × 109 mol−1 dm3 s−1) and selenoxide (2.5 × 108) quenched the Type II reaction of butyrophenone through a charge-transfer process more efficiently than the corresponding sulfide (1.5 × 108) and sulfoxide. The irradiation of 2-(benzylseleno)ethyl benzoylacetate gave bis[2-(benzoylacetoxy)ethyl] diselenide and 1,2-diphenylethane.