Abstract: A description is given of a process for the production of a disinfectant by electrochemical activation (ECA) of water, in that to the water to be disinfected is added an electrolytic solution, particularly a sodium or potassium chloride solution and the water to which the electrolytic solution has been added in the form of a dilute water/electrolytic solution is supplied with an electrical current in an electrolytic reactor with a cathode compartment having a cathode and with an anode compartment having an anode separated spatially from the cathode compartment by applying a d.c. voltage to the electrodes, in order to bring the water/electrolytic solution into a metastable state suitable for disinfection. To bring about a reliable disinfecting action of the electrochemically activated water and with high reproducibility, the invention proposes that the pH-value of the dilute water/electrolytic solution in the reactor anode compartment is controlled to a value between 2.5 and 3.