Experiments on co-combustion of municipal solid waste (MSW) and coal were conducted in a bubbling fluidized bed (BFB). The MSW sample was pretreated through hydrothermal treatment (HT) for obtaining uniform characteristics. MSW blending ratios as 10%, 20%, 30% and 50% were selected and tested at 700, 800, 900 degrees C to verify to which extent coal can be substituted with HT MSW in terms of emissions and unburnt carbon (UC) in fly ash (FA). The results obtained in this study showed that the lowest CO and NO emissions were found at 20% and 30% HT MSW blending respectively. Moreover, the SO2 emissions decreased with the HT MSW addition and the HCl emissions were below 5 ppm. Furthermore, the UC contents decreased at the mixing ratio below 30% at low temperature. Positive synergistic relationships were identified and it is possible to accept 30% MSW combustion in a coal-fired BFB reactor. (c) 2012 Elsevier Ltd. All rights reserved.