The combustion of coal in a mixture of pure O-2 and recycled flue gas is one variant of a novel combustion approach called oxy-fuel combustion. With the absence of N-2, this approach leads to a flue gas stream highly enriched in CO2. For many applications, this flue gas stream can then be compressed and sequestered without further separation. As a result, oxy-fuel combustion is an attractive way to capture CO2 produced from fossil fuel combustion. When coal is burned in this O-2 and CO2 rich environment, its combustion characteristics can be very different from conventional air-fired combustion. In CETC-O, a vertical combustor research facility has been used in the past years to investigate the combustion characteristics of several different coals with this variant of oxy-fuel combustion. This included flame stability, emissions of NOx, SOx, and trace elements, heat transfer, in-furnace flame profiles and flue gas compositions. This paper will report some of the major findings obtained from these research activities. (c) 2005 Elsevier Ltd. All rights reserved.