The sorption of Ca2+ and Mg2+ ions on the silica was studied as a function of concentration and temperature. The extent of sorption of the metal cations was found to increase with the increase in both the concentration and temperature of the system. It was found that the Ca2+ ion with ,ts smallest hydrated radii was able to reach the surface easily and was held more strongly as compared to Mg2+ ion. The sorption of metal cations was accompanied by the release of H' to the bulk phase. The sorption data fitted the linear form of the Langmuir equation. The positive values of M-I for the uptake of the metal ions on Si02 showed their sorption mechanism to be endothermic in nature. Both the positive !'is and negative ~G values conftrmed the spontaneous nature of the sorption process.