About 200,000 bpd (barrel/day) vacuum residue oil is produced from oil refineries in Korea. These are supplied to use asphalt, high sulfur fuel oil, and upgrading residue hydro-desulfurization units. High sulfur fuel oil can be prepared by blending oil residue with light distillate to bring fuel oil characteristics in the range of commercial specifications, which will become more stringently restrictive in the near future in Korea. Vacuum residue oil has high energy content; however, due to its high viscosity, high sulfur content and high concentration of heavy metals are representative of improper low grade fuel, which is considered difficult to gasify. At present, over 20 commercial scale IGCC (Integrated Gasification Combined Cycle) plants using feedstocks with vacuum residue oil for gasification are under construction or operating stage worldwide. Recently, KIER (Korea Institute of Energy Research) has been studying the vacuum residue gasification process using an oxygen-blown entrained-flow gasifier. The experiment runs were evaluated under a reaction temperature of 1,200-1,250 ℃, reaction pressure of 1.0 kg/cm2, oxygen/V.R ratio of 0.8-1.2 and steam/V.R ratio of 0.4-0.7. Experimental results show a syngas composition (CO+H2), 77-88%; heating value, 2,300-2,600 kcal/Nm3; carbon conversion, 95-99, and cold gas efficiency, 68-72%. Also, equilibrium modeling was used to predict the vacuum residue gasification process and the predicted values reasonably well agreed with experimental data.