A kinetic reaction mathematical modeling of the gasification process of bamboo in a downdraft fixed bed gasifier is carried out, considering the main reactions occurring in the reduction zone, to predict the producer gas composition and the variation of species in the length of the thiszone. The model is developed using drying, pyrolysis and combustion as input data taken from previous research, and a chemical and physical characterization of bamboo as a biomass resource. The model is solved with differential equations solving software, and the output predictions are validated with experiments made in the same downdraft gasifier, using air as the gasifying agent, and taking temperature profiles at every zone (drying, pyrolysis and combustion and reduction) and gas species concentration data of the output produced gas.