The invention relates to a process for the preparation of 2-chloro-5-chloromethyl-thiazole, which is employed as intermediate in the preparation of compounds having a pesticidal action, which process comprises reacting a compound of formula (II), in free form or in salt form, (III), (IV), (V) or (VI) with a chlorinating agent, where R and M+ are as defined in claim 1; to the compounds of the formulae (III) and (IV), which are used in this process as intermediates; and to the use of, and a process for the preparation of, the compounds of formulae (III) and (IV).