Abstract: A new-type spectroelectrochemical cell--Fiber-optic Spectroelectrochemical cell(FOSECC) was developed. Using this cell, we investigated the absorption spectra of Fe(CN)₆^3-/Fe(CN)₆^4- with the changes of the applied potentials. The formal potentials and the numbers of electrons transferred at various temperatures were determined and the thermodynamic functions of this electrochemical systems were derived from the results obtained. The sensitivity of this cell expressed with molar absorbance/potential ratio was worked out. All the results were satisfactory.

Key words: Fiber-optic spectroelectrochemical cell, Fe(CN)₆^3-/Fe(CN)₆^4-system, Thermody- namic functions, Molar absorbance/potential ratio