Hydrogen production via steam reforming of bio-oil is a potential method to reduce the dependence on the conventional fossil fuels. To investigate the reactivity of bio-oil and its difference with gasification tar and conventional fossil fuels, the steam reforming of various compounds (benzene, toluene, m-xylene, m-cresol, n-hexane, cyclohexane, 1-propanol, and acetic acid) was conducted in a fixed-bed flow reactor at various temperatures over a high-performance RuNi/BaOAl2O3 catalyst. 1 As a whole, the reactivities of these compounds in steam reforming decrease in the following trend: n-hexane > cyclohexane > I benzene > toluene > m-xylene >1-propanol > m-cresol > acetic acid. For the C6 hydrocarbons, benzene showed a lower reactivity than n-hexane and cyclohexane, due to the stable benzene ring. The reactivities of aromatic hydrocarbons decrease with the addition of methyl groups to the benzene ring due to electronic and steric effects. m-Cresol showed a lower reactivity than benzene, toluene, and m-xylene, suggesting that the incorporation of a hydroxyl group to the benzene ring hindered the steam reforming reaction. Besides the steam reforming reactions, the side reactions such as hydrogenolysis, demethylation, decomposition, and methanation of CO and CO2 also occurred. A benzene ring can be formed by the dehydroaromatization of n-hexane or cyclohexane, while the reverse reaction cannot occur due to the thermodynamic limit. The largely containing acetic acid in bio-oil needs a higher reforming temperature than the other compounds and is easy to be thermally decomposed into coke at low temperatures, which increases the difficulty of bio-oil steam reforming.