This dataset contains the raw and processed data, as well as model parameters, corresponding to the AIChE Journal manuscript re-submitted in 2026 after peer-review entitled “Modeling the separation of water-in-oil emulsions in continuously fed gravity settlers using millifluidic experiments”. The data include measurements of DPZ height, droplet coalescence rate, flow rates, and demulsifier concentrations. It also provides theoretical modeling results used for Figures 3,5,7,8,9,10,11,12,13 in the article. Note that the number of figures has been modified and updated to match the revised manuscript.The figures have been revised, reorganized, and renumbered to ensure consistency with the final accepted manuscript. A new Figure 5a has been introduced, and the previous Figure 5 has been redesignated as Figure 5b. Former Figures 8 and 10 are now presented as Figures 7a and 7b, respectively. Former Figures 10 and 12 have been renumbered as Figures 9a and 9b. Former Figures 13 and 16 have been renumbered as Figures 11 and 13.