Ammonia has been stripped from aqueous solutions in a semibatch reactor with steam. This reactor system has proven to be an economical design for smaller users. Data have been collected in a laboratory-scale reactor at different conditions of steam flow rates, liquid volumes, pH, and temperature. A mathematical model of the reactor has been developed, and the experimental results are compared with theoretical values. The liquid phase is described by either a perfectly mixed model or a finite dispersion model. The steam is modeled as a plug-flow system. The best match between experimental results and the model has been obtained for the finite dispersion model, and this model is proposed for design and scale-up applications.