Since tar elimination from the product gas is necessary to make gasification an attractive option, the presence of tar was included in a kinetic model. Lignin was assumed as the main precursor of tars due to its aromatic nature; therefore, the lignin content of biomass was considered as part of the fuel characterization. This work shows the results from the simulation of the fluidized bed gasifier that incorporates the proposed mechanism for tar formation and evolution into the kinetic model. Model results were compared with experimental data from wood gasification. The comparison showed that the model was consistent with what was expected during the evolution of primary tars according to experimental work from previous reports. However, the model overestimated tars of class 2 and the total tar concentration.