Bitumen emulsification experiments have been carried out in a continuous pilot scale rotor-stator facility. The effects of the following process parameters, namely the temperature of the aqueous phase and bitumen, the rotor speed, the dispersed phase content, the bitumen grade and the emulsion flow rate were investigated. For each process parameter, the trends obtained for the Sauter diameter (d(32)) were compared with those available in the literature on emulsification. A new correlation to predict the droplet size was also proposed. It was shown that the droplet viscosity during emulsification, the rotation speed of the rotor and the dispersed phase content have a significant effect,on the droplet size. (c) 2005 Elsevier B.V. All rights reserved.