PURPOSE: To produce nitriles from aldehydoximes under nearly neutral and mild conditions in high efficiency by using a haloiminium salt as a dehydration agent.

CONSTITUTION: A nitrile (e.g. 3-nitrobenzonitrile) is produced by using a compound of formula (R1 and R2 are lower alkyl; X is halogen; (n) is 2 or 3), e.g. 2-chloro-1,3-dimethylimidazolinium chloride or 2-chloro-1,3-dimethyl-3,4,5,6- tetrahydropyrimidium chloride as a dehydration agent, adding about 1mol of the compound of formula and about 2mol of a base (e.g. pyridine or triethylamine) to 1mol of an aldehydoxime compound (e.g. 3- nitrobenzaldehydoxime) and making the components to react with each other at room temperature or thereabout.