The use of nickel-loaded brown coal char (Ni/BCC) as a catalyst for tar reforming has been studied under mild conditions in a laboratory-scale fluidized bed gasifier using steam as the gasifying agent and nitrogen as the product gas carriers. Characterization of the catalyst was performed in a fixed-bed reactor under various conditions such as Ni/BCC particle size in the range of 0.5 to 2 mm and pyrolysis temperature in the range of 823 to 1023 K in order to investigate the effect of both catalyst particle size and pyrolysis temperature on crystallite size of Ni/BCC. The Ni/BCC catalyst was consumed at various steam feed rate so as to determine the effect of steam feed rate on the size of the catalyst. The XRD pattern of the catalyst showed that the size of the Ni particles increases as the particle size of the catalyst decreases, pyrolysis temperature increases, and steam feed rate increases. SEM images and BET surface area were used to characterize the surface structure and surface area of the Ni/BCC catalyst, respectively. The space velocity and catalytic tar reforming temperature as a function of gas yields were investigated. The catalyst showed high and stable catalytic activity and produced a high-quality product gas with space velocities of 10000 and 4000 h(-1) at 923 and 873 K, respectively.