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Abstract Reforming tar molecules into smaller gaseous molecules has been a critical challenge for biomass energy utilization. Hematite (α-Fe2O3) has been demonstrated as an effective catalyst for the catalytic reforming of tar, nevertheless, the detailed mechanism of α-Fe2O3 catalyzed tar reforming remains unclear. In this work, we apply the density functional theory method to investigate this problem. Specifically, we study both (0001) and (01 $$\overline{{\text{1}}}$$ 2) surface structures of α-Fe2O3 and then use the structures to investigate the adsorption and C–C bond cleavage of benzene on these surfaces. Our results show that the dominant interactions between benzene and a single Fe-terminated (0001) surface are van der Waals forces, yet benzene could be chemisorbed on the Fe and O co-exposed (01 $$\overline{{\text{1}}}$$ 2) surface via strong C–O interactions. As a result, the (0001) surface is not active towards benzene cleavage, whereas the (01 $$\overline{{\text{1}}}$$ 2) surface can promote the aromatic C–C bond breaking. Furthermore, our calculations indicate that chain-like alkene species and carbonyl species are the two types of potential products that form after the C–C bond cleavage of benzene on the α-Fe2O3 (01 $$\overline{{\text{1}}}$$ 2) surface, with the activation energy of 1.78 eV and 2.62 eV, respectively. In summary, we reveal the importance of co-adsorption on both Fe and O centers and oxidative addition on C–C bond cleavage of aromatic compounds on the α-Fe2O3 surface, which provides novel insights into the mechanisms of tar cracking on oxide catalysts.