Co　catalyst　supported　on　BaAl12O19　(BA)　showed　higher　activity　in　the　steam　reforming　of　tar　from　the　pyrolysis　of　biomass　than　those　supported　on　Al2O3,　ZrO2,　SiO2,　MgO,　and　TiO2.　Characterization　results　indicate　that　the　Co　metal　particles　supported　on　BA　had　high　dispersion,　although　the　surface　area　of　Co/BA　was　small.　High　dispersion　of　Co　metal　particles　on　BA　can　account　for　the　high　steam　reforming　activity,　and　this　high　dispersion　is　related　to　the　strong　basicity　of　the　BA　surface.　Strong　basicity　of　BA　and　high　dispersion　of　Co　metal　particles　on　BA　are　connected　to　high　H2O　reactivity　to　form　H2,　probably　at　the　interface　between　Co　metal　and　BA.　In　addition,　the　Co/BA　catalyst　exhibited　higher　reusability　through　the　coke　combustion　and　the　subsequent　reduction　treatment　than　the　Co/Al2O3　catalyst.　This　is　attributed　to　the　suppression　of　the　solid　reaction　between　the　oxidized　Co　and　BA.©　2013,　Hydrogen　Energy　Publications,　LLC.　Published　by　Elsevier　Ltd.