The stability of the adsorption of three anions (nitrate, bromide, and chloride) on chemical manganese dioxide (CMD) was studied using a two-variable, two level factorial design. The two variables were the concentration and pH of the solutions of the sodium salt of the anions. The concentration CMD was varied from 1 M–0.001 M and the pH from 3.5–2.5. 84, 67, and 54 % variations in the adsorption ... [Show full abstract] of Br–, NO3–, and Cl– on CMD, respectively, were obtained. Independently, the concentration and pH affected the electric surface charge. However, their combined influence has a negative and low effect. The surface response plots of the model equations, which did not show the optimum values for concentration and pH, reinforced this observation. The highest stability of the anions was observed when concentration and pH were at their minimum values of 0.001 M and 2.5, respectively.