Here a palladium-catalyzed oxidation method for converting alkylarenes into the aromatic ketones or benzaldehydes with water as the only oxygen donor is reported. This C-H bond oxidation functionalization does not require other oxidants and hydrogen acceptors, and H2 is the only byproduct. The oxygen atom introduced into the products is confirmed to be from water by the MS analysis on the product of the 18O-labeled water reaction.