Ozone-assisted catalytic oxidation of toluene was conducted over MnOx/gamma-Al2O3 to identify and differentiate the role of reaction byproducts. It was found that not only alumina acted as a reservoir for toluene, but also it interacted effectively with toluene to create surface carboxylate intermediates. Surface carboxylates were essential for an effective oxidation process, and they did not directly cause catalyst deactivation. The presence of Mn sites was necessary for further oxidation of the surface carboxylates. At 90 A degrees C, a stable catalytic activity with 95% conversion was achieved. However, at 25 A degrees C, byproducts such as acetic acid and formic acid accumulated on the surface of the catalyst and decreased the catalyst activity [GRAPHICS] .