Improved process development and design of technologies such as pyrolysis and gasification of lignocellulosic biomass can be aided greatly by advanced comprehension of their chemistry and thermal reactivity. Hemicellulose and lignin have significant chemical variations within plant species and after biomass treatment, which are outside of the capability of most pyrolysis kinetic models . This study creates a chemical/physical kinetic model that can (i) be readily adapted to numerous types of lignocellulosic biomass, and (ii) offer detailed information of product distribution and composition within a satisfactory level of accuracy. A detailed lumped-mechanistic model, i.e. Ranzi's kinetic model of biomass pyrolysis , was used to adapt the use of new pseudo-components of hemicellulose and lignin, including acetyl side-chains, uronic acids, hexose carbohydrates, and guaiacyl-model compounds. The new pseudo-components and their corresponding stoichiometric product distribution were defined to more accurately reflect chemical features that correlate with different biomass groups and their properties, as determined using different characterisation techniques, such as chemical hydrolysis, Nuclear Magnetic Resonance and thermogravimetric analysis. Through this approach, biochemical characterisation of biomass can be implemented to extend the applicability and to improve the accuracy of semi-empirical kinetic models for biomass pyrolysis.