The project objective is to evaluate operational parameters affecting contaminant control during staged, cyclone, coal combustion simulating direct coal firing into a gas turbine. A two stage, horizontal cyclone coal combustor has been operating at 5 and 7 MMBTu/hr thermal input. First stage carbon conversion was about 100% at stoichiometric air/fuel ratio, and it decreased with decreasing first stage air/fuel ratio. The bulk of the unburnt carbon particles were carried over into the second stage, where complete oxidation occurred as determined by gas analysis. With staged combustion, the measured NO/sub x/ measured at the second stage exit was reduced, for example, by 57% at a 65% stoichiometric air/fuel ratio. In addition, the benefits of staging for NO/sub x/ control were enhanced when second stage gas temperature was minimized, either through the use of high second stage dilution air, or by maximizing first stage carbon conversion, which reduced char particle carryover. Post test analysis of the slag indicates that most of the coal alkalies were retained in the slag. A high organic sulfur coal was used in these tests and over 90% of the coal sulfur was converted to SO/sub 2/ in the second stage, with no sorbent injection. With limestone injection into the second stage, nearly 100% SO/sub 2/ reduction was measured at economical Ca/S ratios. Second stage sorbent injection tests indicate that second stage temperature is a major factor in sulfur capture. With sorbent injection in the first stage, measured SO/sub 2/ in the first stage was reduced by up to 64% at about 70% stoichiometric ratio, at economical Ca/S ratios. The significance of these results are that they help identify combustor operating parameters, as well as their range of values for conditions applicable to gas turbine operation.