Tannic acid is a exact formation of tannin, a font of polyphenol. Its infirm acidity (pKa all 6) is appropriate to the numerous phenol groups in the structure. The chemical method in behalf of commercial tannic acid is ordinarily foreordained as C76H52O46, which corresponds with decagalloyl glucose, but in information it is a amalgamating of polygalloyl glucoses or polygalloyl quinic acid esters with the digit of galloyl moieties per molecule ranging from 2 up to 12 depending on the bed out source second-hand to extract the tannic acid. Commercial tannic acid is chiefly extracted from any of the following plant parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves (Rhus coriaria).

According to the definitions provided in external references such as international pharmacopoeia, Provisions Chemicals Codex and FAO-WHO tannic acid monograph 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 mistaken expend of the term. It is a yellow to light brown amorphous powder.