Activity of manganese oxide supported on ${ u}-Al_2O_3$ was increased when cerium was added. Also, cerium-added manganese oxide on ${ u}-Al_2O_3$ was more effective in oxidation of toluene than that without cerium. XRD result, it was observed that $MnO_2+CeO_2$ 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 ${ u}-Al_2O_3$ changed significantly increased at a lower temperature. The activity of $18.2 wt{\%};Mn+ 10.0 wt{\%};Ce/{ u}-Al_2O_3$ increased at a lower temperature. The cerium added on the manganese catalysts has effects on the oxidation of toluene.