THE PRESENT work aimed at throwing some light on chemical …… behavior of montmorillonite clay mineral (Mont.), calcium carbonate (CaCO3) and humic acid (HA) upon equilibrating each of them with different concentrations of Ni under different pH values. Retained amounts of Ni were calculated as the difference between the applied Ni concentrations and the corresponding remained concentrations in the solution. Both Freundlich and Langmuir isotherm equations were used for describing the relationship between the adsorbed amounts of Ni per unit weight of the adsorbent and concentration of Ni in the equilibrium solution. The results revealed that the amounts of Ni adsorbed by the examined materials increased gradually with increasing concentrations of Ni in the equilibrium solution under the different studied pHvalues. Also, adsorbed amount of Ni per unit weight of the different studied adsorbents increased with increasing the pH values. The examined materials revealed different sorption capacities for Ni according to their nature and ambient pH value. Also, the examined materials showeddifferent adsorption maxima as well as different affinities for Ni at the different pH values. It could be concluded from the obtained results that application of additives such like those investigated herein may be helpful in ameliorating soils contaminated with heavy metals such as Ni through changing most of its available content to retained (unavailable) content and hence limiting its transport to plant and consequently the food chain.