Papaverine hydrochloride, C20H21NO4•HCl, is a white, crystalline powder, odorless, with a slight bitter taste and is soluble in water.

Papaverine hydrochloride is the hydrochloride of an alkaloid obtained from opium or prepared synthetically. It belongs to the benzylisoquinoline group of alkaloids. It does not contain a phenanthrene group as do morphine and codeine.