Atromentic acid is a red-orange pigment found in fungi within the Boletales group.

Variants include homoatromentic acid.

This pigment has been studied and elucidated by Wolfgang Steglich and colleagues over decades.

[2] When atromentin is oxidised with hydrogen peroxide a yellow product is produced.

A sodium hydroxide solution is also yellow, but when this is neutralized with acid the red atromentic acid crystallises.