The aim of this study is to determine the effect of the main chemical components of biomass: cellulose, hemicellulose and lignin, on chemical kinetics of biomass pyrolysis. The experiments were designed based on a simplexlattice mixture design. The pyrolysis was observed by using a thermogravimetric analyzer. The curves obtained from the employed analytical method fit the experimental data(R2N 0.9). This indicated that this method has the potential to determine the kinetic parameters such as the activation energy(Ea), frequency factor(A) and reaction order(n) for each point of the experimental design. The results obtained from the simplex-lattice mixture design indicated that cellulose had a significant effect on Eaand A, and the interaction between cellulose and lignin had an important effect on the reaction order, n. The proposed models were then proved to be useful for predicting pyrolysis behavior in real biomass and so could be used as a simple approximation for predicting the overall trend of chemical reaction kinetics. The aim of this study is to determine the effect of the main chemical components of biomass: cellulose, hemicellulose and lignin, on chemical kinetics of biomass pyrolysis. The experiments were designed based on a simplexlattice mixture design. The pyrolysis was observed by using a thermogravimetric analyzer. The curves obtained from the employed analytical method fit the experimental data (R2N 0.9). This indicates that this method has the potential to determine the kinetic parameters such as the activation energy (Ea), frequency factor (A) and reaction order ( The results obtained from the simplex-lattice mixture design indicated that the cellulose had a significant effect on Eaand A, and the interaction between cellulose and lignin had an important effect on the reaction order, n. The proposed models were then proved to be useful for predicting pyrolysis behavior in real biomass and so could be used as a simple approximation for predicting the ove rall trend of chemical reaction kinetics.