This study presents the results obtained from the operation of a 20 kWth in situ gasification chemical-looping combustion (iG-CLC) unit with a Chinese bituminous coal as the fuel and a natural iron ore as the oxygen carrier. This unit was built based upon the concept of a novel iG-CLC system evaluated through our previous cold-model tests. It is mainly composed of a high-flux circulating fluidized bed riser as the fuel reactor, a cross-flow moving bed as the air reactor, and a combination of an inertial separator and a cyclone separator as the separation system. The actual thermal power inputs from the coal for the reported tests in this study were about 11 kWth and the total duration reached about 70 h. The flow patterns and reaction characteristics of the whole system were investigated, and the effects of the fuel reactor temperature on the distributions of gas components in the two reactors were elucidated. At the fuel reactor temperature of 950 degrees C, the CO2 yield, gas conversion, carbon capture efficiency, and total solid fuel conversion reached high values at 90.47%, 92.77%, 97.12%, and 98%, respectively. During the reported tests, the iron ore exhibited adequate reactivity and oxygen transport capacity, good cyclic stability, low tendency for agglomeration and high resistance to attrition.