The temperature dependence of surface charge isotherms in the system where PZC and CIP do not coincide was subjected to a quantitative theoretical-numerical analysis. That analysis, based on the TLM model of the oxide/electrolyte interface, and on the assumption of the 2-pK charging mechanism, would suggest that the relation (pK(a1)(int) + pK(a2)(int))/2 = PZC may no longer be preserved in this system. However, the existence of CIP may still be used to develop interrelations between equilibrium constants of various surface reactions, The observed linear relationship between CIP and electrolyte concentration is very useful in estimation of these constants, Also, linear dependences of PZC and pH(CIP) on 1/T were found. Their theoretical-numerical analysis leads to the conclusion that in this system no enthalpic effects accompany the attachment of the anion to the doubly protonated surface oxygen, and the adsorption of cation on the empty surface oxygen.