Manufacture of isocyanate

A process for the production of tertiary aralkyl isocyanates which comprises reacting a halide of the formula ##STR6## in which X represents a halogen atom, R.sub.1 and R.sub.2 represent the same or different hydrocarbon radicals selected from normal, branched and cyclic alkyl groups, and phenyl, naphthalyl and higher aryl groups, and can be joined to form substituents forming cyclic compounds, such bivalent substituents being selected from--(CH.sub.2).sub.n --where n is an integer from 3 to 5, ##STR7## and R.sub.3 represents an aromatic hydrocarbon groups selected from phenyl, naphthalyl, higher fused ring aryl and biphenyl groups, polycyclic aromatic hydrocarbon groups of the formula ##STR8## in which Y represents a bivalent radical selected from ##STR9## wherein m is an integer from 1 to 3, and such aromatic groups having halogen, methyl, methoxy substituents or substituents of the formula ##STR10## with a stoichiometric excess of isocyanic acid in a solution in a solvent for said halide and isocyanic acid.