Abstract: The adsorption isotherms for benzyl alcohol, anisole, benzaldehyde and benzoic acid on silica gel from cyclohexane have been measured at 15℃ and 30℃. The standard changes of free energy △G°, enthalpy △H° and entropy △S° in adsorption processes have been calculated from the Langmuir parameters. The results indicate that △S° is all positive. The shifts △VOHof the adsorption band of the stretching frequency of free hydroxyl groups on silica gel at high surface coverages were determined. The results show that △H⁰ is linear function of △v_OHor △v_OH^1/2.