Char derived from cyanobacterial blooms (CDCB), by-product of fast pyrolysis of cyanobacterial blooms from Dianchi Lake (Yunnan Province, China) at a final pyrolysis temperature of 500 degrees C were used as feedstock material in this study. Steam gasification characteristics of CDCB were investigated in a fixed-bed reactor to evaluate the effect of particle size (below 0.15 mm, 0.15-0.3 mm, 0.3-0.45 mm, 0.45-0.9 mm, 0.9-3 mm) and solid residence time (3, 6, 9, 12, 15 mm) on gas yield and composition, and experiments were carried out at bed temperature range of 600-850 degrees C, steam flow rate of 0.178 g/min. The results showed that solid residence time played an important role on steam gasification process, while particle size presented less effect on gasification process; proper particle size and longer residence time were favorable for dry gas yield and carbon conversion efficiency (CCE). At the same time, higher reaction temperature reduced influence of particle size on gasification process, and smaller particle size required less residence time for reaction completed. Maximum dry gas yield and CCE reached 1.84 Nm(3) kg(-1) and 98.82%, respectively, achieved at a temperature of 850 degrees C, flow rate of 0.178 g/min, solid residence time of 15 mm and particle size range of 0.45-0.9 mm. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.