Abstract: A set of thermo-electrochemical (TEC) equations for the cell and half-cell reactions has been derived. Is is shown that the difference between the enthalpy change determined by TEC technology and the one calculated with the current thermodynamic data of ions of any half-cell reaction in electochemical systems is coastant. The absolute entrupy change of the standard hydrogen electrode reaction was determined to be 85.2 J.K-1 .mol-1 at room temperature:

Key words: thermo-electrochemistry, absolute entropy, standard hydrogen electrode