The objective of this study is to simulate biomass gasification in a concentric tube reactor using a phenomenological approach supported by computational fluid dynamics simulation tools. The solid biomass is modeled using a Lagrangian scheme based on the discrete phase model, while the gas phase is modeled using an Eulerian framework that allows continuous phase interaction. A first-order kinetic model for biomass pyrolysis was also proposed, which implemented an intermediate species Vol(g) from which the pyrolysis gas composition was established using mass balances and empirical correlations for the gas equilibrium ratio. The syngas composition obtained from the simulation was validated with experimental data from a concentric tube gasifier, resulting in a composition of CO=16.92%, H 2 =11.38%, and CH 4 =5.96%, with a weighted error ranging from 2.4% to 8.8%. It is essential to highlight that this study presents a distinctive feature regarding the reactor employed because the concentric tube reactor is an option unexplored in the literature in fixed-bed biomass gasification. Keywords: Gasification, Computational Fluid Dynamics, Concentric Tubes, Biomass, Pyrolysis, Discrete Phase Model DOI： https://doi.org/10.35741/issn.0258-2724.58.5.30