Aluminum-saturated Wyoming bentonite, suspended in a solution of NH4Cl, KCl, or LiCl, was adjusted to a range of degrees of base saturation with the respective hydroxide. The distribution of the cations between solution and pH-independent exchange sites could be represented satisfactorily by an equilibrium distribution equation when the monovalent ions were NH4 or K but not when they were Li. The ion product (Al) (OH)3 was smaller at low base saturation, and increased to about 10−33.0 with NH4 and K but to only 10−33.7 with Li. The monovalent base potential (pH–pM) was a function of the magnitude of (Al) (OH)3 and the distribution constant, as well as the degree of base saturation.