A model for simulating reburning in semi-industrial scale has been developed. It consists of a recently developed reaction mechanism for reburning with C-1 and C-2 hydrocarbons, in combination with ideal reactor modeling and a simplified mixing approach. The reaction mechanism as well as the mixing model has been validated separately against experimental data from laboratory and pilot scale tests. Modeling predictions have been compared with experimental data from a number of pilot scale studies of gas reburning with good results. The large differences in reburn efficiency reported in different low-temperature pilot scale experiments are reconciled in terms of the different operating conditions used. The model has been used to assess the potential of the reburn process at low temperatures, and recommendations for process optimization are provided. Results show that the low-temperature gas reburn process has a significant potential for NO reduction and that both the reburn and burnout regions are important in process optimization.