Activity of manganese oxide supported on γ-Al2O3 was increased when cerium was added. Also, cerium-added manganese oxide on γ-Al2O3 was more effective in oxidation of toluene than that without cerium. XRD result, it was observed that MnO2+CeO2 crystalline phases were present in the samples. For the used catalyst, a prominent feature has increased by XPS. TPR/TPO profiles of cerium-added manganese oxide on γ-Al2O3 changed significantly increased at a lower temperature. The activity of 18.2 wt% Mn+10.0 wt% Ce/γ-Al2O3 increased at a lower temperature. The cerium added on the manganese catalysts has effects on the oxidation of toluene.