Permanganic acid has also been prepared through the reaction of hydrofluorosilicic acid with potassium permanganate,[4] through electrolysis, and through hydrolysis of manganese heptoxide, though the last route often results in explosions.

[5] Crystalline permanganic acid has been prepared at low temperatures as the dihydrate, HMnO4·2H2O.

As a strong acid, HMnO4 is deprotonated to form the intensely purple coloured permanganates.

Potassium permanganate, KMnO4, is a widely used, versatile and powerful oxidising agent.

Permanganic acid solutions are unstable, and gradually decompose into manganese dioxide, oxygen, and water, with initially formed manganese dioxide catalyzing further decomposition.