High valency iron-containing perovskite catalyst BaFeO_3−δ could efficiently promote the additive-free oxidative CC bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O₂ as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.