Abstract Catalytic activities of Ni- and Ni–Fe bimetallic based catalysts supported by palygorskite, MgO–Al 2 O 3 , La 0.8 Ca 0.2 CrO 3 , and La 0.8 Ca 0.2 CrO 3 /MgO–Al 2 O 3 toward the cracking and reforming of naphthalene and toluene (as biomass tar model compounds) as well as real biomass tar from pyrolysis of eucalyptus wood chips were studied. At 700-900 °C, the main products from the cracking of these hydrocarbons are H 2 , CH 4 , C 2 H 4 , C 2 H 6 , and C 3 H 6 . Among all catalysts, Ni–Fe supported by MgO–Al 2 O 3 and La 0.8 Ca 0.2 CrO 3 /MgO–Al 2 O 3 show the highest H 2 yield values and good resistance toward carbon deposition. Additions of H 2 O and CO 2 can promote steam and dry reforming, from which H 2 and CO were the major products from the reaction and the amount of carbon formation was considerably reduced. Importantly, the H 2 O/tar and CO 2 /tar ratios strongly affect the H 2 yield value, particularly for Ni–Fe/La 0.8 Ca 0.2 CrO 3 /MgO–Al 2 O 3 due to the presence of perovskite-based La 0.8 Ca 0.2 CrO 3 . At proper H 2 O/tar and CO 2 /tar ratios, La 0.8 Ca 0.2 CrO 3 behaves like the partly-reduced metal-oxide catalysts and promotes the reforming activity. Addition of O 2 along with H 2 O and/or CO 2 can further reduce the carbon formation and increase the H 2 yield. Nevertheless, excess O 2 could oxidize metal particles and combusted H 2 to H 2 O, which causes lower H 2 yield production.