In order to develop the system to be used in the production of monopotassium phosphite and dipotassium phosphite salts formed as a result of the exothermic neutralization reaction of phosphorous acid and potassium hydroxide, the unknown elements of the reaction were determined, the type of operation in which the reaction will be carried out, and the stoichiometric ratio were determined. To find the reaction kinetics, phosphorous acid and potassium hydroxide solutions were prepared in different concentrations and experiments were carried out. Experiments were carried out in semi-batch and batch and continuous operating modes to investigate the relationship between the heat released by the reaction and the operating modes. In order to observe the effect of explosion and splash that may occur as a result of exothermic reaction, and to evaluate product specifications, experiments were carried out both feeding acid on base and feeding base on acid. It was found that there was no difference between the two experimental sets. Also, it was shown that the reaction stoichiometry should be carried out in a 1: 1.5 (acid: base) molarity ratio, Instead of a semi-batch reactor system, a tubular reactor has been designed in a tubular reactor system that will ensure that the reactants are fed at certain intervals throughout the reactor, thus preventing sudden explosion, splashing, temperature rise and reaction speed, and at the same time increasing the product efficiency with this feeding method. As a conclusion the desired pH value of 6.5 was reached, the temperature in the reactor was controlled, and the product containing potassium and phosphorus at the desired concentrations was obtained.