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In this study the effects of parameters such as coal loading (wt.%), the initial pH of mixture, the addition of various electrolytes, surfactants and temperature on the viscosity and rheologic parameters of coal–water mixture (CWM) have been investigated. The apparent viscosity was measured with a RV8-Brookfield rotating type viscosimeter. The additives used were AlCl₃ and K₂HPO₄ as the electrolytes and Cetyltrimethyl Ammonium Bromide (CTAB), Sodium Dodecyl Sulphate (SDS) and Borrosperse NA-3A as the surfactants. It was found that the most effective additives, in terms of the viscosity reduction, were CTAB and K₂HPO₄, and that the CWM which had coal concentrations up to 50% (based on the weight of dry coal) could be prepared by using each additives. In addition, the viscosities of CWM with increasing temperature were found to increase at low speed, and decrease at high speed.