A rigorous thermodynamic interpretation based on the triple-layer complexation model is given of the experimental heats of adsorption recorded in various types of calorimetric experiments. Also, theoretical expressions are developed describing temperature dependence of the measured surface charge. Our theoretical description is based on a model of an energetically homogeneous sui-face, i.e., the surface oxygen has identical adsorption properties. The developed equations are applied to reproduce the temperature dependence of some experimentally measured surface charge isotherms to prove to what extent the triple-layer model of adsorption on a homogeneous oxide surface is able to reproduce the behavior of the actual adsorption systems.