In organic chemistry, mandelonitrile is the nitrile of mandelic acid, or the cyanohydrin derivative of benzaldehyde.

Small amounts of mandelonitrile occur in the pits of some fruits.

Mandelonitrile is the aglycone part of the cyanogenic glycosides prunasin and amygdalin.

Prunasin can be hydrolyzed by the enyzme prunase into glucose and mandelonitrile (for example, when an appleseed is digested in a ruminant's stomach).

In a one pot reaction, benzaldehyde is reacted with sodium bisulfite to give the corresponding adduct, which further reacts with aqueous sodium cyanide to give the racemic product:[4]