Three kinds of three-dimensional (3D) Mn 2 O 3 catalysts with different morphologies (cube, fan-like structure, and sphere) and various exposed crystal planes were prepared by a hydrothermal method for benzene oxidation. The activity results suggested that sample Mn 2 O 3 -Cl with hierarchical cube morphology exhibited a better rate of benzene degradation than the other samples. Mn 2 O 3 -Cl exhibited the lowest complete benzene conversion temperature (T 90 = 252 C), which was $48 C lower than that of the Mn 2 O 3 -S sample.Meanwhile, the R m and R s values of Mn 2 O 3 -Cl were 2.71 and 3.21 times, respectively, higher than those of Mn 2 O 3 -S. TEM results suggested that morphology has a significant effect on crystal planes. The activity-morphology relationship over the Mn 2 O 3 samples was investigated by multiple analytical techniques. It can be concluded that the low crystallinity, superior redox ability, abundant low-valence Mn ions, and O latt species in the Mn 2 O 3 -Cl catalyst were responsible for its superior catalytic activity.