An industrial process for the direct chlorination of ethylene at low temperatures to yield 1,2-dichloroethane has been considered. The reactor, whose configuration corresponds to a bubble column with external recirculation loop, has a working capacity of 19 m(3) and a production capacity of 54 000 tons of 1,2-dichloroethane per year. In order to describe its operation, the predictions from a model developed in a previous work were evaluated using a special analysis of experimental data. This enables to obtain both a model and a numerical simulation program which not only predict various performance variables with satisfactory relative errors but also have the capacity of representing the influence of changes in operating conditions adequately within the entire technically feasible operating range.