This paper analyzes the countercurrent single-stage bubble column reactor (BCR) for gas-liquid ozonation systems. The effects of system variables on ozonation performance are examined. The aspects of ozonation performance considered include the efficiency of ozone utilization, the efficiency of pollutant removal, and the emission concentration of ozone gas. This analysis takes into account the effects of ozone decomposition and the ozonation of pollutants on the ozone mass transfer (i. e., enhancement factror, E-r), the variation of pressure (P) and of gas velocity (U-G) along the column, and dispersion effects (Pe(G), Pe(L)). The obtained detailed single-stage BCR model may be used in further development of multi-stage BCR model in the future. The results of this study can provide useful information for rational design of a BCR ozonation contactor, and are important with respect to the treatment of pollutants via ozonation. For the simplified case without ozonation of pollutants, this analysis reduces to that of Huang et al. (1998).