I think you measure the voltage of the working electrode with respect to the reference electrode i.e.voltage difference between working and reference electrode (not between working and counter electrode)

Between working and counter, the voltage is easy to measure since there's some current flowing- any moderately high input impedance voltmeter will do for macroscopic electrodes. For working versus reference, things are more difficult because the current is near zero; here, you need an electrometer-type measurement.

This is why electrochemical equipment costs $$$.

The simplest way is to use a potentiostat, which supplies the voltage and the current produced by the redox reaction.

The applied voltage cane be fixed or swept. The cost of these instruments vary from affordable to expensive. You can find schematics on the internet published by universities that are not difficult to fabricate. In addition if you hook into wilkepedia and look up voltammetry, you will get a detailed understandable description of the whole process.

Easy, while you are making the measurement, you can connect a Voltimeter of high impedance between the working electrode and secondary electrode.

it seems to me your question is related to the LSV technique in a 3electrode setup. first of all, using a reference elctrode, you have to calculate the potential range you want to apply to your working electrode vs. a used reference. the cell current can be measured very easely using a potentiostate. the reference electrode allways have a constant potential (don't forget to calibrate in your cell and a used electrolyte) and you get the signal of the current flow on the working electrode via the counter electrode. a resulting curve should be current on the working vs potential applied.

You can simply connect a voltmeter in the working electrode and counter electrode, operated in parallel with their 3-electrode electrochemical system. Is a cheap solution but of course always there are more sophisticated solutions.

The working electrode is generally held at ground (0) with respect to the outside world. So any modern digital voltmeter can determine the voltage of the auxiliary electrode by measuring that relative to the circuit ground. Why would you want to do this? You need not involve the ref or working electrodes. Of course you are measuring the potential of the electrode itself and NOT the absolute (interfacial) potential difference between that auxiliary electrode and the solution, which is IMPOSSIBLE to meaure.

Purchase potentiostat, it will give u the voltage and current after measuring.

I think you have a good point. In that the counter electrode during electrochemical measurements have not received much attention.

The size and shape of the working electrode also varies and it depends on the application.........

Why don't you simply include the second reference electrode into measuring? Connect it to the counter electrode, measure the potential of counter electrode with independent voltmeter, and then simply calculate E(WE-CE).

I am quit sure exactly by simply connect a voltmeter between the working electrode and counter electrode. For simply using the drawing showed with Mr. Rodrigo De Souza comments.

The potentioal difference is measured between the WE and the reference electrode, never between WE and CE..

For Mr. Robert Sandulescu, thank you very much for your comment. You are right what you measure with potentiostat is the potential between WE and RE, but this not meaning there is no potential or you can not measure the potential between the WE and CE!!

I think if you want to measure the potential on the WE at a particular current (let's say 5 microamps) in a simple three-electrode CV setup which has identical WE and CE in a close proximity to each other (single-compartment cell), you need to find the potential on CE at which your current is -5 microamps. This potential has to be equal to the potential on WE relative to the quasi-reference electrode (at 5 microamp current). This has to be true because of the symmetry of the setup, the way I see it. If your WE and CE electrodes are different or are in different compartments, then you can switch WE and CE (just switch the leads of the potentiostat) and re-measure the CV curve to find at what potential you pass the -5 microamps current through your system (and that is the potential you are looking for). The way I see it this can all be done without the extra voltmeter (just using the same potentiostat). I'm not sure though what new information you will obtain by measuring this potential (at least in case of a single-compartment 3-electrode cell).

the purpose of potentiostat is to keep the potential difference between WE and RE for few moments during which the current flowing through CE is measured and then repeat stepwise so that a graph of flowing current versus stepwise potential is plotted .. this is a principle of voltammogram showing a peak of current at fixed potential... if you try to measure the potential difference between WE and CE, you should remember the formula of voltage=current x resistance, then at certain potential where current flowing as electrons through redox reaction will change voltage abruptly without control .. at this point, what do you imagine the relation between volt and current will be?

Do you really need to measure the potential between the WE and CE? Generally potential difference between WE and RE is measured in any of the voltammetric techniques.

The potential will depend of the surface area of the secondary electrode expose of the electrochemical reaction. Remember, the potentiostat will adjust the voltage to keep the module of the current on the SE at the same on the WE but the sign oppositive. Higher area of the SE - lower voltage, and minor area - higher voltage. You can see, for example in a simple aqueous reaction such as redox reaction of metals/ion metals, when reduce area on SE, the evolution of gas is more intensive because the potential is on the onset of the evolution of Hydrogen or Oxygen, depending if the reaction on the WE is an oxidation (Evolution of Hydrogen on SE), or a reduction (evolution of Oxygen on SE).

Very good your answer Mr. Suarez. I agree with you.

Of course you can always measure the voltage between RE and CE or WE and CE, you should just care that the reference electrode is not polarised, e.g. that the current flowing through stays in pA/nA Range.

Obviously measuring the voltage between WE and CE is much better when you have a normal potentiometer

and you have reasonable currents that you measure

Common Voltmeter is not such a good idea(see above), a high impedance voltmeter such as an electrometer is a much better idea for measuring RE CE voltage

Depending on the potentiostat there might be some possibility to also measure the RE CE or WE CE voltage directly.

If you want to prevent a reaction to happen at your counter electrode use a diaphragm around it (maybe there are also some CE that include some solution removal such that you avoid a contamination with generated species to the bulk electrolyte)

With a four electrode setup you have a "two reference system" and control the potential in between both (Sense versus REF)

The sense electrode is normally connected directly to the working electrode

but can be used with a second reference electrode in liquid liquid cells

If you stick in a second reference (as Mihael Bucko suggested) you have the advantage that you don't mess up with your potentiostat when you are drawing current from the reference with a multimeter but I think measuring WE CE is and substracting the applied potential from it is usually much better

Hello everyone, I am going to start Electrochemical impedance spectroscopy (EIS) and I will use VersaStudio software. I am new user to do EIS. Can any one help me in basics? I have Ag/AgCl electrodes. Do I need to buy RF (SCE) as well? Looking for your kind suggestions.