Two detailed pyrolysis models are used to predict pyrolysis products of the conversion of two biomass fuels in a drop tube reactor. In both models, biomass is considered as a combination of the reference components cellulose, hemicellulose and lignin, but their mathematical modelling approaches are different. Two distinct methods are used to estimate the composition of the biomass fuels based on their ultimate and proximate analysis. A heat balance is applied to the particle, considering convective and radiative heat transfer along with drying effects. A tar cracking model was used in a post-processing step. The results obtained using different combinations of pyrolysis models and methods to estimate the composition were compared to experimental results. All combinations used under-estimated the total volatile yield, and the tar cracking model is necessary to capture the final yields of gas and tar. Finally, the predicted pyrolysis products very sensitive to the composition of the biomass.