The effect of glass composition on physico-chemical properties of surface layers formed through reaction between strong acid and several silicate and aluminosilicate glasses was studied through transmission-IR, ATR-IR, XPS, SIMS, and nano-indentation analyses. It was shown that aluminum is depleted from the surface while molecular water is diffused into the surface layer of glasses with high levels of aluminum. Nano-indentation experiments indicated that the hardness of the surface layers were decreased compared to that of the bulk region and the degree of the softening was more significant in the high aluminum glass.