Abstract: The present invention relates to a process for the preparation of high-grade chloramine by the action of commercial eau de Javelle of 100 chlorometric degrees on a solution of ammonia in the presence of ammonium chloride. According to this process, the chloramine is obtained having a content greater than or equal to 2 mol L−1, that is to say, greater than or equal to 10.3%. The process can be carried out continuously or discontinuously.