Phase Separation Time is a characteristic parameter of a two-phase liquid-liquid extraction system essential to evaluate the solvent pair suitability in a solvent extraction process and the process throughput in a mixer-settler system. A novel light scattering technique to determine the phase separation time unambiguously has been developed for the first time at the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. The technique rests on the principle that dispersed mixture of two phases result in high scattering of an incident beam of light, and this scattering decreases as the dispersed phases coalesce. By monitoring the intensity of this scattered light at 90 degrees to the incident light, the "Phase Separation Time" can be deduced.