Adsorption of sulfate by three red soils carrying variable amounts of electrical charge at constant pH in the pretence of Cl^- ions was studied.The hydroxyl ions released from Red earth,lateritic red earth and latosol accounted for only 12%,14% and 20% of the amounts of sulfate adsorbed by the three soils respectively.For a latosol at pH 5.0,the change in electrical charge accounted for 64-82% of the adsorbed sulfate.It is suggested that most of the sulfate was adsorbed through the displacement of coordinated water molecules in the surface of soil particals.