A kinetic model was proposed to optimize the integrated bioreaction-crystallization process newly developed for production of calcium gluconate crystals using external loop airlift columns. The optimal operating conditions in the bioreactor were determined using an objective function defined to maximize the productivity as well as to minimize biocatalyst loss. The optimization of the crystallizer was carried out by matching the crystallization rate to the optimal production rate in the bioreactor because the bioreaction was found to be the rate controlling process. The calcium gluconate productivity under the optimal conditions of the integrated process was obtained by the simulation based on the process model. The productivity of the proposed process was found to be comparable to that of the current batch fermentation process.