In this study, the catalytic effect of chars from the co-pyrolysis of Indonesian coal and biomass [giant leucaena wood (LN)] on the biomass-derived tar decomposition was investigated using a two-stage fixed-bed reactor. The catalytic performance of the coal char (CC), LN biomass char (LNC), and coal/LN blended chars (C/LN) at three different weight ratios on the catalytic tar cracking under nitrogen (N-2) and tar steam reforming under a steam/N-2 mixture was studied. The C/LN showed a better catalytic role for tar decomposition than the CC and LNC. The high coal fraction [3:1 (w/w) C/LN] blended char had a good catalytic effect on both tar catalytic cracking and tar steam reforming because of its high surface area and silicate forms of the alkali and alkaline earth metals (AAEM) on the char. On the other hand, char with a high biomass ratio [1:3 (w/w) C/LN] also had a good catalyst activity in tar steam reforming because of the high steam activation of the char surface and the AAEM would be in the form of phenolates.