A quantitative treatment pertaining to the study of thermodynamics Of adsorption of sulphorhodamine-B, acid red-4 and acid green-25 on activated silica gel through the evaluation of the Gibbs free energy, DELTAG, as a function Of temperature is presented. The DELTAG values are computed by employing the Gibbs adsorption equation by making use of the areas under the m-1nCs curves. The enthalpy, DELTAH, and the entropy, DELTAS, has also been calculated. The results are discussed in terms of the nature of the adsorbates.