In a reactive crystallization, the reaction rate influences the supersaturation level and thus the crystallization process and product quality. This work aims to determine reaction kinetic parameters for the Li2CO3 crystallization from Li2SO4 and Na2CO3 solutions using a calorimetric method. Experimental tests were carried out in a reaction calorimeter, under isothermal conditions, at different temperatures (333, 343, and 353 K) and initial concentrations for both reactants (0.7, 0.92, and 1.05 mol/L). Reaction enthalpies and specific heat of mixtures were experimentally determined as well as reaction rates from thermal conversion data. Furthermore, kinetic parameters such as activation energy (56.8 kJ/mol), frequency factor (1.35 X 10(8) L-0.48/min mol(0.48)), and reaction orders were calculated. The contribution of this work is to provide useful kinetic data that are not reported in the scientific literature, which are critical in the modeling and control of reactive crystallization process for the Li2CO3 production from lithium sulfate sources.