The wet hemihydrate phosphoric acid process was modeled and simulated with some assump- tions and simplifications. The process consisted of grinding unit, reaction section, filtration section, and hydration unit and steady-state operation was assumed. Modeling was based on actual operation data and models for each unit were combined to form the overall closed system. Results of simulations showed that the model developed in this study decribed the behavior of actual plant very well. Various sensitivity analyses for the fundamental parameters were performed using the model. In grinding section, the effect of specific break- age rate on particle size distribution was examined. It was possible to regulate the temperature of slurry at reaction and hydration stage by using slurry recycle ratio. The effects of the recycle ratio on phosphoric acid concentration were also investigated.