The electrostatic dehydration of crude-oil emulsions were investigated using pilot-plant and industrial data. The experimental data obtained with seven different crudes over a wide range of viscosities in a pilot plant showed that the electric field and the residence time were the most important operating variables. Various crude-oil properties influenced the emulsion stability, including the total acid number and the resin, asphaltene, and metal contents, but their effects were statistically correlated with the crude-oil viscosity and density. Using pilot-plant data, a power-law model relating the water content in the treated oil to the dehydration operating conditions and the crude-oil viscosity and density was developed to aid in the design and evaluation of industrial units. The model was tested against industrial data and found to be able to predict very well the performance of the industrial units.