In the present work, the optimization of different structural and process parameters of a divided wall column (DWC) for the energy efficiency has been presented. The optimal design and operation of divided wall distillation columns involve a number of variables and is a non-linear problem. Rigorous simulation of a DWC was carried out using Multifrac model of ASPEN Plus software. Box-Behnken design (BBD) under response surface methodology (RSM) was used for the optimization of the parameters and to evaluate the effects of these parameters and their interactions on the energy efficiency of a DWC. The process variables were found to have significant effect on the energy efficiency of a DWC as compared to the effect of structural variables, and the predictions from the BBD optimization agree well with the results of the rigorous simulation. (C) 2012 Elsevier Ltd. All rights reserved.