PURPOSE: To obtain a compound useful as a raw material for thiourea and a synthetic intermediate for pharmaceuticals and agricultural chemicals in high efficiency by reacting a dithiocarbamic acid amine salt with a haloiminium salt as a dehydrosulf idization agent.

CONSTITUTION: The isothiocyanates can be produced by reacting a haloiminium salt of formula I (R1 and R2 are lower alkyl; X is halogen; (n) is 2 or 3) with a dithiocarbamic acid amine salt of formula II (R3 is organic group; B is amine). The use of the haloiminium salt of formula I as the dehydrosulfidization agent enables the reaction at nearly neutral pH under moderate condition. The produced isothiocyanate can be used as a raw material for thiourea compound without purification.