NOVELTY - The method comprises feeding a heated start-up medium to a gasifier operating at a first temperature, transferring heat from the heated start-up medium to the gasifier to increase the temperature of the gasifier from the first temperature to an intermediate temperature sufficient to auto-ignite a start-up fuel, feeding a start-up fuel and an oxidant to the gasifier after the temperature within the gasifier is increased to the intermediate temperature, and combusting a portion of the start-up fuel within the gasifier to produce a combustion gas.    USE - The method is useful for starting a gasifier, which is useful for gasifying hydrocarbon feedstock such as biomass (e.g., plant and/or animal matter and/or plant and/or animal derived matter), coal (e.g., high-sodium and low-sodium lignite, lignite, subbituminous and/or anthracite), oil shale, coke, tar, asphaltene, low ash or no ash polymers, hydrocarbon-based polymeric materials and/or by-products derived from manufacturing operations.    ADVANTAGE - The method is capable of easily starting the gasifier without sulfur emission.    DETAILED DESCRIPTION - The method comprises feeding a heated start-up medium to a gasifier operating at a first temperature, transferring heat from the heated start-up medium to the gasifier to increase the temperature of the gasifier from the first temperature to an intermediate temperature sufficient to auto-ignite a start-up fuel, feeding a start-up fuel and an oxidant to the gasifier after the temperature within the gasifier is increased to the intermediate temperature, combusting a portion of the start-up fuel within the gasifier to produce a combustion gas, transferring heat from the combustion gas to the gasifier to increase the temperature of the gasifier to an operating temperature, which is sufficient to gasify a portion of a hydrocarbon feedstock, recovering a cooled start-up medium from the gasifier, compressing the cooled start-up medium, re-heating a portion of the cooled start-up medium to produce the heated start-up medium, recycling the heated start-up medium to the gasifier, feeding the hydrocarbon feedstock to the gasifier after the gasifier is heated to the operating temperature, combusting a portion of the hydrocarbon feedstock to produce another combustion gas, gasifying the portion of hydrocarbon feedstock to produce a syngas product, stopping the introduction of the start-up fuel once feeding the hydrocarbon feedstock has started, circulating particulates comprising sand, ceramic materials, ash, crushed limestone and/or inorganic oxides through the gasifier, and increasing a pressure within the gasifier from a first pressure to an operating pressure as the temperature within the gasifier is increased from the first temperature to the operating temperature. The step of re-heating the cooled start-up medium comprises: combusting the start-up fuel to produce a combustion gas; and indirectly transferring heat from the combustion gas to the cooled start-up medium to produce the heated start-up medium. The intermediate temperature is 500-650 degrees C, and the operating temperature is 850-1200 degrees C.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a gasification system for gasifying hydrocarbon feedstock.    Combustion zones (111)    First heat exchanger (118)    Mixing zone (135)    Second mixing zone (140)    Transfer line. (153)