Nowadays, the occurrence of harmful algal blooms is increasing rapidly all over the world. However, the methods of resource utilization of algae are very few. In this study, we propose a new way to dispose algae, which is gasification of coal-algae slurry. Coal slurries prepared with algae were investigated, and gasification reactivity of coal-algae slurry was compared with that of coal-water slurry (CWS). The results showed that, anaerobic fermentation, chemical treatment, high-speed shearing and heating are effective pre-treatment methods on reducing the viscosity of algae, which could obviously increase the maximum solids concentration of coal-algae slurry. When the de-ionized water/algae ratio is 1:1, the maximum solids concentration could get to 62.5 wt.%, which is almost the same as that of CWS. All the coal-algae slurries exhibit pseudo-plastic behavior, and this type of fluid is shear-thinning. Compared with CWS, the stability of coal-algae slurry is much better, which could be no solids deposition after 70 h. The coal-algae slurry displays better gasification reactivity than CWS. (C) 2009 Elsevier Ltd. All rights reserved.