A mathematical model of biomass gasification kinetics in bubbling fluidized beds has been developed. It is one-dimensional, as it is capable of predicting temperature and concentration gradients along the reactor axis, and considers two phases, a bubble and a dense phase. In addition to the reaction kinetics in the dense phase, mass transfer between the two phases and a quantitative estimation of local bubble and particle properties are included in the model. A theoretical optimization with respect to ER, pressure, bed height and gas velocity has also been performed. Finally, a comparison with experimental data from the literature was done, which showed a largely satisfactory agreement, though further validation is still required.