PURPOSE: To produce the compound in a high yield and a high purity which is an important intermediate useful for producing an active compound for plant protection.

CONSTITUTION: In the process in which 2-mercaptobenzothiazole and 2- mercaptobenzoxazol of the formula I (R3 and R4 are each H, 1-4C alkyl, 1-4C alkoxy, NO2, F, Cl, Br, SO2Cl, SO3H, CN or SO2-1-4C alkyl; X is O or S) is chlorinated with thionyl chloride, these compounds are reacted in 50-1000 wt.% based on the compound of the formula I of a solvent or diluent, in the presence of 0.001-5 mol.%, especially 0.01-0.8 mol.% of phosphorous compound of the formula YP(OR5)2 (R5 is 1-12C alkyl, phenyl or 7-10C aralkyl; Y is H or OR5), using 0.8-3 mol.%, especially 1-1.2 mol.% based on 1 mol of the compound of the formula I of thionyl chloride at a temperature of 30-140°C to produce 2-chlorobenzothiazole or 2-chlorobenzoxazol of the formula II (R1 and R2 are each R3 or R4 excepting SO3H).