The present work involves the preparation of a highly concentrated coal-water slurry employing three different low-rank coals of Indian origin having variable ash content. The formulation, rheology, and stabilization of the slurry have been investigated using saponin extracted from the seeds and pericarps (mods) of the Acacia concinna plant as a dispersant. The saponins extracted from both the seeds and pericarps of the plant are found to stabilize the slurry. The theological characteristics of the slurry have been analyzed by varying pH and coal loading in the presence and absence of saponin. The coal-water slurry follows the Bingham plastic model and behaves as a non-Newtonian fluid in the presence of saponin. The stabilization of the coal-water slurry has been attributed primarily to the diminution of the coal particle-particle interaction because of steric hindrance offered by adsorbed saponin. The measurements of zeta potential, yield stress, and viscosity of coal in the presence of saponin further provide evidence to this effect.