Methods have been developed for the determination of-the two main parameters of dispersions, viz., drop size distribution and entrainment content. The reliability of laser diffraction spectroscopy for measuring the drop size distribution was proved, using a liquid-liquid system which corresponded to that of the PUREX process, where the diffraction indexes of the liquids are similar. Coulometric titration was used to determine the entrainment content; a thermodynamic correction was found to be necessary.