Extractive reaction has interesting potential for biodiesel synthesis as the temperature window for the optimum process does not require reaching the distillation state, the high reaction temperature deteriorates the fuel property and the consumption of non-edible oils faces free fatty acids hurdle. This paper reports the characterization of flooding properties of the liquid-liquid system of palm oil and ethanol. Determination of the Sauter diameter of ethanol and oil droplet in the excess oil or ethanol, coalescence factor of excess volume in various ratios, and hydrodynamics in cylindrical viscometer were carried on. Sauter diameter of 2 mm was measured for both ethanol and oil droplets in oil and ethanol phases, respectively, with the speed of 7.29 x 10^-3 m s^-1 and 7.3 x 10^-1 m s^-1, respectively. The Sauter diameter value suggests the use of minimum 5 mm of the aperture of theoretical plate. The test on ethanol-oil mixing revealed a maximum time elapsed for phase settlement at the ethanol:oil volumetric (EOV) ratio of 1:1 and linear response with 0.78 slope of liquid-holdup versus the EOV ratio. The phase settlement result indicates the highest risk of flooding at equal amount of volume of both phases. Viscosity test on the mixtures with various EOV ratios revealed pseudo-plastic behaviour attributed to the shear thinning and the hypothetical viscosity of pure oil shows 25% of the actual one.