Abstract: Using potassium chloride and thermal phosphoric acid as raw materials，the double decomposition reaction process to prepare potassium dihydrogen phosphate was studied.Influences of reaction time，reaction temperature，and mix ratio of materials on the conversion rate of potassium chloride were investigated.Under the conditions of the reaction temperature at 373~413 K and the reaction time at 1~4 h，the macroreaction process of potassium chloride and thermal phosphoric acid was studied.Self?鄄impeding effect played an important role on the reaction rate，and its coefficient（β） increased with the increasing temperature.Drozdov equation was selected to simulate the reaction data and the dynamic equation was confirmed：1/t ln［1/（1-X）］-βX/t=exp（-65 840/RT）+2.215.Apparent activation energy （Ea） was 65.84 kJ/mol，and the mode was reliable.Study was expected to reveal the related mechanism of the preparation for potassium dihydrogen phosphate with potassium chloride and thermal phosphoric acid，so as to provide a necessary theoretical basis for the design of reactor and for optimization of processing conditions.

Key words: potassium dihydrogen phosphate, reaction kinetics, activation energy