There is described a method for ensuring and monitoring electrolyzer safety and performances in a manufacturing process which uses at least one electrolyzing cell containing at least one cathode and at least one anode separated by a membrane, comprising the step of: determining a safe single voltage operation range depending of the current and corresponding to the normally working electrolyzing cell; determining a reference voltage deviation depending on the time derivation of the current; measuring the voltage over time at the terminals of the electrolyzing cell; determining the measured voltage deviation by calculating the time derivative of the measured voltage; comparing the measured voltage to the safe single voltage operation range and the measured voltage deviation to the reference voltage deviation over time; stopping the manufacturing process when the measured voltage is outside the safe single voltage operation range or the difference between the measured voltage deviation and the reference voltage deviation is outside a predetermined range or a single voltage behavior is different than the average of a group of reference cells.