The effect of electrolyte coagulants and flocculants on coal surface properties was investigated through measurements of contact angles and zeta potentials at various amounts of reagents and pH values. Results obtained show that maximum contact angles for the coals studied occur in the alkaline pH range (pH > 7) for the conditions investigated. Contact angles increased up to coagulant and flocculant concentrations of about 60 and 80 ppm by weight, respectively, and thereafter remain almost constant at higher concentrations. These studies indicate that the adsorption of flocculants occurs through physical interaction with the coal surface, possibly due to hydrophobic bonding, while the adsorption of coagulants could be attributed to hydrogen bonding. Coagulants probably affect flotation of coal fines adversely, whereas flocculants have a remarkable effect on contact angles similar to that of surfactants.