More than 70% of the total electricity production in Greece is based on the utilisation of soft brown coal of medium ash content (approximate to 15%), high moisture (approximate to 58%) and low calorific value (4.5-5 MJ kg(-1)). The increasing demand (twice the EC average) for electrical power imposes the need for the best exploitation of the existing brown-coal surface mines, together with new ones producing solid fuel of the same or even lower quality. This fact, combined with the high cost of the DeNO(x)/DeSO(2) facilities required when the conventional pulverised-fuel combustion technology is applied, implies a need for investigating the applicability to the particular coal quality of alternative coal-combustion technologies such as fluidised-bed combustion. This paper presents the results of combustion tests on Greek lignite in two CFBC (circulating fluidised bed combustor) facilities. The first, a laboratory-scale facility of approximately 100 kW thermal power, is at NTUA (the National Technical University of Athens); the second, which is of semi-industrial scale (1.2 MW thermal power), is al RWE＇s power station at Niederaussem in Germany. The two installations are of different size and different design, and the concepts represent the major CFBC construction trends: the Niederaussem facility operates with a thermally insulated (＇hot＇) cyclone, whereas the CFBC in Athens features a non-insulated (＇cold＇) cyclone. The results reported in this paper include determination of the operating conditions to achieve proper fuel burnout, examination of the influence of air-staging on the temperature distribution inside the reactor, and investigation of the combustion behaviour of the particular fuel type in relation to the size of fuel particles. As regards pollutant emissions, the CO, SO2, NOx and N2O emissions are recorded during Various test cases for both facilities. Particular interest applies to the examination of additives of various types in order to obtain the maximum SO2 retention inside the reactor, because the fuel that was used has a high sulphur content (1.5%). Several conclusions are drawn concerning the necessary modifications and requirements of the plant layout when a large-scale CFBC installation is designed to burn low-grade brown coat. The air-staging, furnace cooling, reactor height and cyclone type are considered the critical parameters for proper ignition and burnout conditions. Note, however, that the results in-this paper are not exclusively of industrial interest: they also include documented experimental data from various test cases, which can be used for the evaluation of computational models aiming to simulate the combustion of coal in CFBCs.