South Australian low-rank coals have high sulfur and high sodium contents, which cause operational problems when the coals are combusted. Fluidized-bed combustion (FBC) of these coals allows for efficient combustion and for convenient sulfur removal by the addition of in-bed sorbents, such as limestone or dolomite. However, the presence of sodium may result in operational problems for FBC because sodium compounds, such as sodium sulfate, which is present in the coal ash, may cause the bed particles to become "sticky" and lead to a loss of bed fluidization. Combustion experiments have been performed in a laboratory-scale fluidized-bed combustor for two South Australian low-rank coals: Kingston and Lochiel. This work was undertaken to compare the behavior of these two coals and to allow for comparisons to previous experience gained using Lochiel coal in both laboratory experiments and pilot-plant operation. Kaolinite-rich clay additives were used in these experiments in an attempt to alleviate the problems associated with sodium present in coals. The effect of refreshing and removing the bed material without interruption of the combustion process was also studied experimentally. Kingston coal showed better performance in the FBC process than Lochiel coal. The ash layer formed from FBC of Kingston coal was found to be less sticky than that formed by Lochiel coal, resulting in longer defluidization times for Kingston coal than for Lochiel coal when no clay additives were used. Kingston coal was able to be combusted at 850 degrees C with the addition of clay at 5% of the total feed rate and with the addition/removal of bed material at 5% of the total feed rate. Analysis showed that the sodium from the coal had reacted with the kaolinite in the clay to form nepheline, a high-melting-point solid compound, which thus restricted the formation of liquid sodium sulfates in the bed. The results of this study show good agreement with the results of previous studies that showed that the addition of kaolinite-rich clays led to problem-free combustion of Lochiel in both small- and pilot-scale operations at 800 degrees C.