Drop size distributions and phase separation were determined in a batch stirred tank with water/paraffin oil using optical measurement techniques. Temperature was varied from 20 °C to 80 °C and dispersed phase fractions up to 0.7, resulting in a phase inversion from oil-in-water to water-in-oil emulsions. Higher temperatures only increase Sauter mean diameters by 9.9%, but reduce phase separation time up to 67.4%. Higher dispersed phase fractions lead to bigger drop sizes and longer separation time. The interplay between drop size distribution characteristics and the phase separation process is investigated in detail. The performance of an existing phase separation model which considers physical properties and the initial Sauter mean diameter was evaluated, showing quite satisfying predictive power. Its predictive power might be further increased by including more information about the whole drop size distribution in future studies.