Although phytoliths exhibit an important control on silicon cycle in superlicial continental environments, their thermodynamic properties and reactivity in aqueous solution are still poorly known. In this study, phytolith is obtained by dry ashing at 400°C. Surface charge represented by zeta potential (C) was investigated under the influences of pH, cations and anions. The results have shown that phytolith' surface contains large number of negative sites (C = -60 mV). Cation adsorption makes surlace charge become less negative, and C values was found to change from negative to positive in relatively low concentration of aluminum. Adsorption of cations onto phytolith surlace decreases in the order: Al+ Ca2+, Mg2+ K+, Na+. On the other hand, anions can be retained on the surlace by bonding with Si4+. Citrate, Cl and acetate show a preference to be sorbed onto phytolith as compared to oxalate, SO4 and NO3. For halogen anions, sorption ability decrease by following order: F Cl Br l. pH affects surface charge by protonantion and deprotonation mechanisms. Surface was found to be more negative if pH increases. Phytolith shows a considerable affinity for both cations and anions. Therefore, this can play an important role for cation and anion exchange capacity of the soil on one hand, and provides nutrients for plants on the other hand.