To elucidate specific functions of supports, we investigated steam reforming of toluene as a model compound of biomass tar over Co catalyst supported on perovskite-type oxide. Co-supported La0.7Sr0.3AlO3-delta catalyst showed the highest activity among various Co-supported catalysts. STEM measurements and XPS measurements revealed the coexistence of La cation and lattice oxygen defect produces an anchoring effect to Co particles. The lattice oxygen release rate on each catalyst was measured with (H2O)-O-18 steady-state isotopic transient kinetic analysis (SSITKA). The anchoring effect, higher dispersion of Co and redox property, are important for the high catalytic performance of Co/La0.2Sr0.3AlO3-delta catalyst on toluene steam reforming. (C) 2017 Elsevier B.V. All rights reserved.