In this study the bubble size distribution and energy dissipation rate are measured in a plunging liquid jet bubble column. The maximum stable bubble diameter in the mixing zone was successfully predicted based on Weber number analysis. A Pareto analysis indicated that the coalescence of bubbles principally occurred as a binary process. The bubble number flux was modeled based on the bubble number concentration, collision frequency of two bubbles of the same diameter, and the probability of coalescence taking place. In general, the predictions were in good agreement with the measurements for both the mixing and pipe flow zones.