Tar decomposition over a dolomite catalyst in gasification conditions was modeled using benzene as a tar model compound. The reactions of the gas main components were included in the models studied. Kinetic studies were carried out at 750-925 degrees C and under ambient pressure in a plug flow reactor using a mixture of simulated gasification gas. Operation conditions without external or internal mass-transfer limitations were applied. Mechanistic models of the Langmuir-Hinshelwood type describing benzene decomposition were developed and tested. Experimental results could be best described by a kinetic rate equation based on the assumption that single-site adsorption of benzene was the rate-determining step and that adsorption of hydrogen inhibited benzene decomposition.