Catalytic oxidation of toluene was carried out to investigate the effect of consecutive run on the catalytic property and performance of 1 wt.% Pt/γ-Al2O3 and the reduced 1 wt.% Pt/γ-Al2O3. The properties were characterized by X-ray diffraction (XRD), the Brunauer Emmett Teller (BET) surface area, temperature programmed reduction (TPR), and transmission electron microscopy (TEM) analyses. In consecutive experiments the second catalytic run resulted in a significant increase of the toluene conversion compared to the first catalytic run, but the toluene conversion in the third catalytic run was similar to that of the second catalytic run. In addition, the reducing treatment of the catalyst led to an increase in the catalytic activity. The increasing catalytic activity in consecutive runs was dependent on the platinum particle size and the oxidation state of the platinum. The increase in platinum particle size during reaction and the reduction in the oxidation state of platinum by hydrogen pretreatment were responsible for the increase in the catalytic activity.