Orsellinaldehyde is a dihydroxybenzaldehyde with a methyl side group.

It can be classified as a resorcinol, benzaldehyde or toluene derivative.

It is a natural product of several fungi.

Fungi that contain it include Grifola frondosa,[1] Aspergillus cleistominutus,[2] Aspergillus nidulans,[3] and Agrocybe praecox.

[4] Orsellinaldehyde can be produced by a Gattermann reaction of orcinol, using zinc cyanide under a hydrogen chloride atmosphere, which adds an aldimine (-CH=NH) group to the ring,[5] followed by hydrolysis to give the aldehyde.