Drop size distribution and Sauter mean drop diameters have been measured in a 113 mm diameter perforated rotating disc contactor for three different liquid-liquid systems. The effects of operating variables including rotor speed and dispersed and continuous phase velocities are investigated. The results show that drop size is strongly dependent on the rotor speed and interfacial tension, but only slightly dependent on the phase velocities. Drop size distributions are appropriately described using normal and log-normal probability density function, and empirical correlations are derived to predict the parameters of the distribution curve as a function of operating conditions and physical properties of the systems. An empirical correlation is also proposed for prediction of the Sauter mean drop diameter in terms of properties of the liquid-liquid systems and operating variables. Good agreement between the prediction and experiments is found for all investigated operating conditions. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.