Phenyl isocyanate is an organic compound typically abbreviated PhNCO.

The molecule consists of a phenyl ring attached to the isocyanate functional group.

Phenyl isocyanate has a strong odor and tearing vapours, therefore it has to be handled with care.

It is used in addition with triethylamine to activate nitro groups to undergo (C,O) 1,3-dipolar cycloaddition (as opposed to O,O).

The nitro group (RCH2NO2) is converted to oxime-like dimers in the reaction:[3] PhNCO is a planar molecule, according to X-ray crystallography.