In this study, the effects of different chemicals that were used as dispersing agent and stabiliser on the stability and viscosity of coal-water slurries have been investigated. In the experiments, anionic type of chemicals-polyisoprene sulphonic acid soda (Dynaflow-K), a derivative of carboxylic acid (AC 1320) and naphthalenesulfonate-formaldehyde condensate (NSF) -were used as dispersing agents and the stabiliser was the sodium salt of carboxymethyl cellulose (CMC-Na). The coal sample used was a bituminous coal (thermal code no. 434) of Turkish origin, with medium volatile matter. The results of the experiments showed that polymeric anionic dispersing agents such as Dynaflow have much greater effect on the viscosity and the stability of coal water slurry. (C) 2003 Elsevier Science B.V. All rights reserved.