The gas-phase partial oxidation (POx) of nascent volatiles (NV) derived from the fast pyrolysis of cedar sawdust at 700 and 800 degrees C was studied both numerically and experimentally. A detailed chemical kinetic model (DCKM) was applied to simulate the POx in a two-stage reactor: the first stage was designed for fast biomass pyrolysis and the second effected the POx of the NV. Analytical pyrolysis experiments were also conducted to approximate the molecular composition of the NV, which is required input for computations using DCKM. The DCKM was modified by an empirical kinetic model for the decomposition of an ill-defined portion of the NV. The kinetic model coupled with a plug-flow reactor model reproduced the observed trends in the product yields with respect to both temperature and oxygen-to-fuel ratio, for not only the major products, but also minor products such as aromatic hydrocarbons which are typically found in the refractory post-gasification tar. (C) 2015 Elsevier B.V. All rights reserved.