Dimanganese trioxide is an active catalyst for removing carbon monooxide and nitrogen oxide from waste gas as an important one of manganese oxides. Its single crystal was synthesized by flux method. Single crystal X-ray diffraction reveals that the compound crystallized in the cubic space group Ia-3 with a=0.94173(11) nm, V=0.83518(17) nm3, Z=48, Dc=5.022 Mg/m3, R(int)=0.0863, R1=0.0659[I>2σ(I)], wR2=0.1929[I>2σ(I)].
