Among different kinds of parameters, the fuel input plays a principal role on the quality of the product gas generated by gasification. Turkish coals have high ash and sulfur contents along with low carbon content and low heating value. The present study investigates the gasification characteristics of four different Turkish coals and also the effects of addition of calcined dolomite on the quality of the product gas. A laboratory scale bubbling fluidized bed gasifier is used to perform gasification tests. Within this frame, air is used as a gasification agent, quartz sand is used as a bed material and the effects of equivalence ratio (ER), coal type and calcined dolomite on gas properties are investigated. The LHV is calculated by using the measured gas compositions. Comparing the gasification performances of four Turkish coals at a fixed ER value, the present study reveals that the ranking is, from the highest to the lowest, Orhaneli, Kale-2, Kale-1 and Goynuk. For Kale-1, the LHV is obtained in the range of 4.36 to 6.16 MJ/Nm(3) for the ER range of 0.44 to 0.17, respectively. The dolomite decreases the tar, H2S and NH3 contents, as well as the LHV of the product gas. (C) 2012 Elsevier B.V. All rights reserved.