The aim of the present work is to investigate the suitability of the UNIFAC method to properly simulate the batch azeotropic distillation of a mixture of acetic acid, water, and ethyl acetate. A batch distillation including upstream countercurrent liquid-liquid extraction was performed at pilot scale. A dedicated analytical method for fast and robust determination of top and bottom products was developed and presented. Experimental data were finally used for the validation of numerical predictions. It could be demonstrated that the UNIFAC method is applicable for the simulation of such a complex transient distillation process.