Pyrolysis of Xanthium strumarium has been performed in a fixed-bed tubular reactor with boron minerals (ulexite, colemanite, and borax) and without catalyst at three different temperatures ranging from 350 degrees C to 550 degrees C with heating rate of 50 degrees C/min. The amounts of bio-oil, bio-char, and gas generated, also the compositions of the resulting bio-oils were identified by GC-MS and FT-IR. The influences of pyrolysis parameters, such as temperature and catalyst on product yields were investigated. Temperature and catalyst were found to be the main factors affecting the conversion of Xanthium strumarium into solid, liquid, and gaseous products. The highest liquid yield (27.97%) including water was obtained with 10% colemanite (Ca2B6O11.5H2O) catalyst at 550 degrees C temperature at a heating rate of 50 degrees C/min when 0.224 > D-p > 0.150 mm particle size raw material and 100 cm(3)/min of sweeping gas flow rate were used.