The present study investigated the production procedure and combustion characteristics of a bio-oil produced through the slow pyrolysis of pinewood. The combustion properties of droplets with different butanol/bio-oil proportions were thus determined and compared. The droplets containing bio-oil varied irregularly in size during combustion and left considerable residue that was also combusted. The duration of combustion was revealed to increase when the bio-oil concentration was increased. The TGA indicated a two-stage weight loss during combustion. The first stage occurred at 30-160 degrees C, corresponding to the endothermic evaporation of the light fraction of the compounds after heating. The second stage occurred at 450-650 degrees C, indicating pyrolytic exothermic residue combustion fed by the macromolecular residue of the interactions between bio-oil constituents. The activation energy was demonstrated to gradually decrease during the evaporation stage and also during the residue combustion stage. The aromatics in the bio-oil polymerized under the intense heat, leading to the formation of residue and soot. The burning rate of the droplet decreased when the bio-oil concentration was increased, whereas the residue burning rate increased with an increase in bio-oil concentration. The volatiles released during residue combustion enhanced the burning rate of residue. (C) 2017 Elsevier Ltd. All rights reserved.