High temperature air-blown gasification is a new concept to utilize the waste heat from gasifier that is called multi-staged enthalpy extraction technology. This process was developed to solve the economic problems due to air separation costs for the oxygen-blown as a gasifying agent. In this study, we have constructed a pebble bed gasifier and operated it by controlling the pebble size and bed height with three different types of coal (Kideco, Datong and Drayton coal). As a result, we can produce syngas with a calorific value of 700 kcal/Nm3 at an air temperature of 650 °C; the performance of high temperature air gasification was strong in the order of Kideco coal, Datong coal and Drayton coal. Also, from the data of the exterior analysis of slag that is attached to the surface of pebbles, we can know that the iron component is considerably high. This means the increase in restored metallic iron component seems to contribute to the solidification of slag.