It is a derivative of benzoic acid and a minor (1%) product of the metabolic break down of aspirin, excreted by the kidneys.

[4] It is also found in the African tree Alchornea cordifolia and in wine.

[5] Gentisic acid is produced by carboxylation of hydroquinone.

Alternatively the compound can be synthesized from salicylic acid via Elbs persulfate oxidation.

In the laboratory, it is used as a sample matrix in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry,[9] and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.