The influence of electrolytes on the dissolution kinetics of samples of commercial Fontainebleau sand consisting of (>99.6 %) silica are studied at (25^{\circ} \mathrm{C}) and over an ionic strength range of (0.01 M) to (1.0 \mathrm{M}) at (\mathrm{pH} 10). The dissolution rates are studied in (\mathrm{NaCl}, \mathrm{Na}{2} \mathrm{SO}{4}), and (\mathrm{CaCl}{2}) solutions and in a stabilized "natural" water using an automated titrimetric method. The dissolution results are analyzed using an electrical double layer model containing options to account for cation complexation of the silica surface and ion-pair formation in the bulk solution. Simplified expressions are given for the surface potential calculated for 1 : 1, 2:1, and 1:2 electrolytes which are used to determine the activities of the ions in the surface plane. The results demonstrate similar effects of (\mathrm{NaCl}) and (\mathrm{Na}{2} \mathrm{SO}{4}) salts on the dissolution rates with a greater than twofold increase over the range of ionic strength studied. In contrast, the results from the dissolution of silica in (\mathrm{CaCl}{2}) solutions show no influence at calcium concentrations between ca. 2 and (70 \mathrm{~m} M) but the dissolution rate increases at high calcium concentrations. The dissolution rate in the natural water is similar to that found in (\mathrm{CaCl}{2}) solutions containing the same calcium concentration. The results support the conclusion that the complexation of (\mathrm{Na}^{+})with the surface of silica is not an important influence on the dissolution reaction, whereas it is necessary to invoke the surface complexation of (\mathrm{Ca}^{2+}) to explain the observed increase of the dissolution rate at higher calcium concentrations. No difference could be determined between the effects of (\mathrm{NaCl}) and (\mathrm{Na}{2} \mathrm{SO}{4}) electrolytes on the dissolution rates expressed as a function of ionic strength or sodium ion concentration. The optimum parameters for the hydrolysis of the ionized and cation-complexed silica, both normalized with respect to the hydrolysis of the neutral silanol groups, are given together with the calculated values of the surface density of the terminal groups. (\mathrm{CaCl}{2}) is shown to enhance the dissolution rate for ionic strengths of (<0.1 \mathrm{M}) relative to (\mathrm{NaCl}) and (\mathrm{Na}{2} \mathrm{SO}{4} .01994) Academic Press, Inc.