Biomass oxidative pyrolysis is of great interest from the point of view of large-scale bio-oil production in autothermal regime. A study has been carried out in thermobalance with different oxygen concentrations (5, 10 and 20 vol.%) in the inlet gas stream in order to analyze the effect of oxygen on the lignocellulosic biomass pyrolysis process and establish a kinetic model for oxidative pyrolysis. The results have been compared with those obtained in inert atmosphere pyrolysis. Firstly, the kinetic pathway has been determined, concluding that pinewood oxidative pyrolysis is the sum of biomass pyrolysis and heterogeneous oxidation plus the combustion of the remaining char. A kinetic model consisting of six simultaneous reactions has been developed, which allows identifying the volatiles released from the joint pyrolysis-combustion of the pyrolyzable and non-pyrolyzable fractions corresponding to hemicellulose, cellulose and lignin. (C) 2011 Elsevier Ltd. All rights reserved.