S-Nitroso-N-acetylpenicillamine (SNAP) is the organosulfur compound with the formula ONSC(CH3)2CH(NHAc)CO2H.

It is a green solid.

[2] SNAP is an S-nitrosothiol and is used as a model for the general class of S-nitrosothiols which have received much attention in biochemistry because nitric oxide and some organic nitroso derivatives serve as signaling molecules in living systems, especially related to vasodilation.

[3] SNAP is derived from the amino acid penicillamine.

S-Nitrosoglutathione is a related agent.