Tannic acid is a exact form of tannin, a font of polyphenol. Its weak acidity (pKa roughly 6) is appropriate to the numerous phenol groups in the structure. The chemical formula in behalf of commercial tannic acid is ordinarily prone as C76H52O46, which corresponds with decagalloyl glucose, but in fact it is a ragout of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on the bed out documentation used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following weed parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves (Rhus coriaria).

According to the definitions provided in extraneous references such as cosmopolitan pharmacopoeia, Food Chemicals Codex and FAO-WHO tannic acid treatise one tannins sourced from the above-mentioned plants can be considered as tannic acid. Sometimes extracts from chestnut or oak wood are also described as tannic acid but this is an false work of the term. It is a yellow to be disclosed brown amorphous powder.