To understand the mechanisnr of NOx reduction by reburning biomass pyrolysis products, the present work is devoted to investigate the capabilities of biomass char, tar, and pyrolysis gas (Py-gas) for NO reduction through experiments in a drop-tube reactor. Pyrolysis of distilled spirit lees at 500 degrees C produced the char and tar tested, while Py-gas was prepared from cylinder gases according to the analysis of experimental Py-gas. The, realized NO reduction efficiency varied with the stoichiometric ratio (SR), reaction temperature, residence time, and initial NO and CO concentrations. At a specified mass rate of 0.15 g/min, tar enabled the best, NO reduction in comparison to char and Py-gas. The presence of CO in Py-gas inhibited the homogeneous NO reduction reactions to cause lower NO reduction efficiency by this agent. For biomass char and tar, their realized NO reduction reactions were promoted, by high temperature and high initial NO and CO concentrations. Moreover, the suitable SR values for obtaining the highest NO reduction efficiency by reburning pyrolysiS products were found to be 0:6-0:8.