Abstract: In recent years research on biodiesel production from non-edible seed oil is receiving more attention to prevent food vs biofuels problems such as starvation in developing countries. Castor seed oil is potential non-edible biodiesel feedstock, but it has high viscosity and high acid value which are among the undesired factors in biodiesel production. The castor seed oil was extracted using soxhlet extraction method, refined using standard analytical methods and its physicochemical properties was determined using ASTM methods. The crude extracts of castor seeds oil which was characterized as high viscous oil, was refined to improve its quality, and physicochemical properties of refined and crude extracts castor seed oil was studies. The crude extracts oil (41.29±1.54%) produce was refined to reduce its high viscosity (233.0±2.00 mm2/s) and acid value (4.488±0.40 mgKOH/g). The viscosity and acid value of the oil significant reduced to 159.0±3.00 mm2/s and 2.805±0.20 mgKOH/g after the refining process. The others physicochemical properties such as flash point, saponification value, iodine value, moisture contents, specific gravity, refractive index, kinematic viscosity, cloud point, pour point and free fatty acids qualities were improved after refining. The study show that refined castor seed oil were more suitable in biodiesel production than crude castor seed oil.Abstract: In recent years research on biodiesel production from non-edible seed oil is receiving more attention to prevent food vs biofuels problems such as starvation in developing countries. Castor seed oil is potential non-edible biodiesel feedstock, but it has high viscosity and high acid value which are among the undesired factors in biodiesel productio...Show More