The co-pyrolysis of pine nut shells (PNS) with scrap tires (ST) at different blend ratios was carried out at 500 degrees C. The addition of ST into PNS in the co-pyrolysis process not only increased bio-oil yields but also improved bio-oil characteristics when compared with the pyrolysis of PNS. The carbon content in bio-oils from all PNS/ST blend ratios was higher and oxygen content was lower than that of PNS-derived oil. This is an indication of the improved characteristics of bio-oils from the co-pyrolysis of biomass with scrap tires. The blend ratio in the feedstock of co-pyrolysis had a significant effect on the product distributions and physico-chemical properties of bio-oils. When heating values of bio-oils produced from the pyrolysis of PNS were compared with bio-oils obtained from the co-pyrolysis of PNS with ST, the addition of ST into PNS led to increase heating values of bio-oils with the exception of PNS/ST (4:1)-derived bio-oil. In addition, the heating values of gas products and levels of hydrogen and hydrocarbons (from C-1 to C-4) in the gas products from the co-pyrolysis of PNS/ST blends were higher than that of the pyrolysis of PNS. The heating values of chars produced from the co-pyrolysis of PNS/ST blends were found to be in the range of 31.1 and 32.9 MJ kg (1). (C) 2014 Elsevier Ltd. All rights reserved.