The catalytic oxidation of 1,3,5-trimethylbenzene (T135MB), which is a simple model of aromatic hydrocarbons, was investigated with a newly designed catalytic jet-stirred reactor (CJSR) equipped with gas chromatography and FTIR at low temperature. Thin film of pure CuO was synthesized at 325 °C using one-step pulsed-spray evaporation chemical vapor deposition. To better understand the interplay between properties and catalytic performances, the obtained catalysts were characterized in terms of crystalline phase, morphology and surface composition. The catalytic performance based on light-off curves revealed that CuO deposited on mesh of stainless steel presented a very high activity against the complete oxidation of T135MB at 330 °C. The induced catalytic effect is attributed to the open porosity, small grain size, abundance of surface adsorbed oxygen of CuO, and the long residence time provided by the newly designed CJSR. Moreover, a possible mechanism was proposed for the complete oxidation of T135MB in CJSR. Accordingly, the combined diagnostic method involving the novel designed CJSR and efficient analysis devices is expected to assist in further understanding of the abatement of complex gaseous pollutants with avoiding high toxic byproducts paving the way for clean combustion applications.