KMnO _ 4 decomposes on heating at 513K to form O _ 2 along with

Potassium permanganate decomposes when heated, the oxidation state of manganese changes as the oxidation state of ${KMnO}_{4}$ is $+ 7$ decomposes to potassium manganate which oxidation state is $+ 6$ and manganese dioxide its oxidation state is $+ 4$.

It is a redox reaction in which $Mn$ which undergo both oxidation and reduction such type of reaction is known as a disproportionation reaction.

$2{KMnO}_{4}\overset{513K}{\to}{K}_{2}{MnO}_{4} + {MnO}_{2} + {O}_{2}$