The feasibility of ammonia injection directly into a fluidised bed coal combustor for thecontrol of NO emissions by selective non-catalytic homogeneous reactions was studied. Experimental runs were carried out using a typical bituminous coal and a low volatile anthracite fired in a 0.3 m square combustor, with the emphasis on the point of injection, the temperature of the reaction zone, and the quantity of NH 3 injected. The ammonia was either premixed with the combustion air or directed horizontally across the fluidising air flow through injectors designed to ensure a uniform distribution of NH 3 over the total width of the combustion chamber. The combustor was operated over an excess air range of −20 to 120% and bed temperatures of 770 to 910°C. The results showed that for NH 3 injection at the optimum location just above the bed surface, a 30 to 50% reduction in the NO levels in the exit flue was attainable for a NH 3 /NO molar ratio of 2 to 4 and a bed temperature of around 825°C. A maximum reduction of 75% was possible by using excess ammonia, but at the cost of increased ammonia emissions. Premixing the ammonia with the combustion air initially resulted in an increase in the NO levels, whilst at higher NH 3 flows, marginal reductions in the NO emission were observed. The presence of excess air was found to lower the extent of NO removal, with optimum reductions occurring at an oxygen concentration of around 3 to 5% at the point of injection. Varying the bed temperature in the range 770 to 910°C did not significantly influence the extent of NO reduction and it is thought that the reductions achieved, especially at the lower bed temperatures, can partly be accounted for by the presence of unburnt volatile fragments (e.g. H 2 , CH 4 ) which are known to enhance the NO/NH 3 reaction.