Abstract: A new and improved process is provided for preparing monochloro-diamino-s-triazines which are useful as herbicides.The process comprises reacting in a first stage cyanuric chloride and a selected monoalkylamine hydrochloride at elevated temperature to give a dichloro-monoalkylamino-s-triazine and reacting in a second stage this dichloro-monoalkylamino-s-triazine with an excess of a different monoalkylamine which may be introduced as a pure liquid, as gas or as a solution in water. The third stage of the process consists of an exchange whereby the monoalkylamine hydrochloride of the first stage and the free monoalkylamine of the second stage are generated. The process gives consistent yields in excess of 97% of monochloro-diamino-s-triazines. Because the process is caustic-free and due to the feasibility of recycling the excess of monoalkylamines employed, no serious effluent problems arise.