In this work, a mechanistic model was developed on the basis of population balance equations for butadiene emulsion polymerization and validated with experimental data in a batch reactor. A combination of finite difference and weighted essentially nonconciliatory (WENO) schemes was used as a precise technique for the discretization of the population balance equations. The obtained values during the evolution of conversion and the average particle diameter values were in good agreement with the measured results for different surfactant concentrations. However, the simulated particle-size distributions (PSDs) were much narrower than the experimental PSDs. Therefore, to match the experimental PSDs, a stochastic term was included in the zero-one model. The effect of surfactant concentration, which is an important factor with a direct impact on the dispersion coefficient, was also investigated and confirmed with experimental results.