Water hyacinth pyrolysis was carried out in a quartz tube reactor. Different particle sizes, pyrolysis temperatures and catalysts were tested. The product fractional yields, gaseous products, surface morphology and crystal structure were analyzed in order to obtain the optimal pyrolysis condition for producing syngas (CO + H-2) from water hyacinth. The results indicated that particle size had a significant impact on water hyacinth pyrolysis and among four particle sizes in this paper dp < 200 mu m was the optimal particle size for syngas production. Moreover, active surface area, porosity level and crystalline materials increased as the temperature rose and the results showed that among five temperatures in this study 900 degrees C was the best pyrolysis temperature for producing syngas. In addition, the syngas production levels can be improved if a suitable catalyst is used. The best catalyst was KCI, followed by CaO and MgO, (C) 2015 Elsevier Ltd. All rights reserved.