Cracking of biomass tar was investigated over Ni/dolomite catalyst prepared by the incipient wetness method using modified dolomite as precursor. Modified dolomite was prepared by mixing Fe2O3 powders with natural dolomite powders to increase Fe2O3 content for higher activity of tar cracking. Four other catalysts (natural dolomite, modified dolomite, ICI-46-1, and Z409) were tested and compared with Ni/dolomite catalyst. The effects of temperature, steam-to-carbon, and space velocity on tar conversion were explored. Ni/dolomite is shown to be very active and useful for tar removal. A 97% tar removal is easily obtained at catalyst temperature of 750 degreesC and space velocities of 12 000 h(-1). The minimum SIC ratio for Ni/dolomite was 2.5 at a catalyst temperature of 750 degreesC to prevent the formation of the coke on the catalyst. No obvious deactivation of catalyst was observed in 60 h on-stream tests. Compared with the Ni-based catalysts (ICI-46-1, Z409), Ni/dolomite catalyst is cheap and has also excellent activity and anticoke ability.