Ethylcholine mustard is a neurotoxic nitrogen mustard that destroys cholinergic neurons. It's the hydrolysis product of the HN1 vesicant.

Under aqueous condition, ethylcholine mustard forms the highly reactive ethylcholine aziridinium (AF64A) ion. AF64A is transported into cholinergic neurons by the choline transporter. AF64A irreversibly inhibits the choline acetyltransferase and thereby inhibits acetylcholine synthesis. AF64A can also produce cytotoxic effects, leading to cell death.

The aziridinium ion can be isolated as picrylsulfonate salt.