Redox measurements are a potentiometrical measurement of the oxidizing/reducing power of a liquid. To be able to measure this equilibrium of reversible redox reactions the electrodes used should be inert. 

Noble electrodes such as Platinum (Pt) and Gold (Au) are widely used for this purpose and seem to approximate the behavior of an ideal inert electrode. 

Platinum is used most widely, has excellent chemical resistance but suffers slightly from chemisorption of Oxygen, which slows down its response. 

The potential of reference electrodes is depending on their composition. A table with the actual values for each system is given next. All values refer to 25° C. The reference system is also indicated on the text plate of the electrode.