This study covers the studies of CWS preparation and combustion properties on the Turkish lignite with low coal calorific (3675 Kcal/kg) value and high ash forming minerals (41 %) that may be regarded as coal wastes. The particle size, coal concentration, air/fuel ratio and atomizing air pressure effects on both slurry preparation and combustion processes were investigated. On preparation of CWS studies the low coal concentration in slurries was reached for a required viscosity and stability values. The slurries with solids concentration of 50 % (by weight) and maximum stability of 7 days were obtained with this kind of coal. But the high combustion efficiencies were reached although the coal property affects the CWS preparation process. Combustion efficiencies ranged from 96,5 % to 99 % were obtained with heat loss of 22 % of total heat produced, although it consists of 60 % water (by weight). With this study it was emphasized that the CWS prepared by low rank coals could be used as fuel without any upgrading processes. © (2005) by the International Pittsburgh Coal Conference.