Catalytic decomposition of tar is a novel technology to clean the gas produced by biomass gasification. The purpose of the present research work was to develop strong and porous pellets of dolomite catalyst for tar decomposition. Porous dolomite pellets of 3 mm in diameter and 4 mm in height were prepared with dolomite, carboxyl methyl cellulose (CMC) and clay. The mechanical strength, the pore rate and the catalytic effect of porous dolomite pellets on decomposition of acetic acid were investigated. When the clay/dolomite mass ratio was 0.4 and the CMC/dolomite mass ratio was 0.2, the porous dolomite pellets had a mechanical strength of 15 N and a pore rate of 0.75 cm(3) g(-1). The pore size had approximately a normal distribution in the range of 0.06-200 mu m. Under the condition of gas residence time at 7.5 s and bed temperature at 800 degrees C, 99.7 wt% of acetic acid was decomposed over the porous dolomite pellets, but only 36.5 wt% of acetic acid was decomposed with natural dolomite particles. It was indicated that the porous dolomite pellets were much more effective than the natural dolomite particles for catalyzing the decomposition of tar to gas. (C) 2010 Elsevier Ltd. All rights reserved.