This paper approaches the evolution of adsorption layer with temperature under different water concentrations. EDX and X-ray diffraction (XRD) indicated that under low water concentration (LWC), there was a sharp decrease in TiO2 quantity curve and grain size curve between 40 degrees C and 60 degrees C. But under high water concentration (HWC), TiO2 quantity and grain size both rose continually. In transmission electron microscopy (TEM) picture, the characteristic of samples of LWC and HWC at low temperature were similar, whereas they became quite different at high temperature. These phenomena manifest that the effects of adsorption and reaction alter at different conditions. Under LWC, adsorption mechanism dominates the process. Under HWC, the chief mechanism at low temperature was similar to that of LWC and at high temperature the major reaction region switches from adsorption to alcohol bulk. Based on the characteristics of adsorption on silica surface, the phenomenology theory dealt with formation of adsorption layer and its evolution with temperature was proposed. (c) 2005 Elsevier B.V. All rights reserved.