A thermodynamic equilibrium model based on evaluations involving C, H, and O element balances and various product species up to C-6 hydrocarbons is reported in this study. This model establishes the effects of biomass composition, temperature, and steam on the various gas product molar fractions. On this basis, most significant parameters determining the chemical interconversions and distribution of chemical species are identified. On the basis of the proposed equilibrium model and using glucose as a model biomass species [C6H12O6], an optimum gasification temperature close to 800 degrees C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. This study has the special value of comparing thermodynamic equilibrium predictions with experimental data obtained in a CREC riser simulator using a fluidizable Ni-Al2O3 catalyst. Results are relevant for scaled-up gasifiers. They show that for reaction times longer than 30 s chemical species are essentially equilibrated and that the proposed model does provide adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 s and the need for nonequilibrium models to describe gasifier performance at such conditions.