Degradation of organic compounds by active chlorine is a feasible technology for elimination of recalcitrant pollutant discharge into the environment. However, the achievement of a highly efficient treatment system requires the development of well-founded reactor design and scale-up methods. Modeling and simulation can provide description of the complex interrelations of phenomena inside the reactor to analyze their behavior and thus help the development of the desired reactors and treatment systems. Thus, in this paper we propose a comprehensive model for active chlorine generation in a filter press type reactor focused on the mass transport coupled with the kinetics of electrochemical reactions and the electrical potential distribution.Two approaches are used: the reactive diffusion migration layer (RDML) model based on the Nernst-Planck equation in laminar regime and the mass transfer wall function (MTWF) model intended to account for the effect of turbulence induced by the inlet and outlet reactor distributors. It is aimed at acquiring detailed space and time information on relevant operating characteristics inside the reactor such as local efficiency, overpotential distribution along the electrode, zones of high current density, among others. The comparison of model results to experimental data show that the MTWF approach predicts better the behavior of chloride oxidation for active chlorine generation and efficiency at 100 and 200 A m(-2) and 0.8 and 1.6 L min(-1) than the RDML model. The predicted generation rate of oxidizing agents allows describing closely the degradation process of Reactive Black 5 as a test system. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.