The conversion of furan (a model of cellulosic biomass) over ZSM-5 was studied in a TGA/TPD-MS system, an in-situ FTIR, and in a continuous flow fixed-bed reactor. The furan adsorbs as oligomers at room temperature with a 1.73 of adsorbed furan/Al ratio. These oligomers are converted to CO, CO2, olefins and aromatics at temperatures from 400 – 600 ºC. We have measured the effects of space velocity, temperature, and partial pressure for furan conversion to help us understand the chemistry of biomass conversion inside zeolite catalysts. The selectivity of aromatics and olefins products did not change significantly with space velocity. The apparent reaction order for furan consumption with respect to furan was lower (1.2) than the apparent reaction orders for aromatics (1.7) and olefins formation (1.5). The apparent activation energies of furan consumption (26 kJ/mol) and coke formation (22 kJ/mol) were lower than the apparent activation energies for formation of olefins and aromatics (50-60 kJ/mol). Coke deposition was fast and dramatically deactivated the catalyst in 1 hour. Kinetic data obtained in this study is strongly pore-diffusion controlled and is far from thermodynamic equilibrium. We have proposed some key elementary reactions that may occur for this process.