Lactic acid is an organic compound with the formula CH3CH(OH)COOH. In its solid state, it is white and water-soluble. In its liquid state, it is clear. It is produced both naturally and synthetically. With a hydroxyl group adjacent to the carboxyl group, lactic acid is classified as an alpha-hydroxy acid (AHA). In the form of its conjugate base called lactate, it plays a role in several biochemical processes.

In solution, it can ionize a proton from the carboxyl group, producing the lactate ion CH
3CH(OH)COâ??
2. Compared to acetic acid, its pKa is 1 unit less, meaning lactic acid deprotonates ten times more easily than acetic acid does. This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group.