Disproportionation reaction, also sometimes called dismutation reaction, is basically a type of redox reaction involving simultaneous reduction and oxidation of atoms of the same element from one oxidation state (OS) to two different oxidation states.

$\stackrel{+6}{3{\mathrm{MnO}}_4^{2-}}+4{\mathrm{H}}^{+}⟶\stackrel{+7}{2{\mathrm{MnO}}_4^{-}}+\stackrel{+4}{{\mathrm{MnO}}_2}+2{\mathrm{H}}_2\mathrm{O}$