Co-firing municipal solid waste (MSW) with bituminous coal and anthracite was conducted using pilot scale circulating fluidized-bed combustion. Both N2O and NO emissions from co-firing MSW with bituminous coal are higher than those obtained from co-firing with anthracite. N2O decreases significantly, whereas NO rises with the increase of Ca/(S + 0.5Cl) molar ratios. Increasing the co-firing rates leads to the reduction of N2O emission, but an increase of NO emission. Raising furnace temperature is an effective way to control N2O emission, but NO emission is scarcely affected. (C) 2004 Elsevier B.V. All rights reserved.